More than 10 feet (3 meters) of muscle, armor, claws and serrated teeth … Now that’s a lizard! Image via Mikhaël Noury/ Pexels.
Let me introduce you to the Komodo dragon, the largest lizard in the world. It can detect food from miles away, hunt large mammals, swim between islands and even produce offspring without a male. Impressive, right? Looking at its size, claws, teeth and prehistoric appearance, the name “dragon” seems pretty fitting.
Growing to more than 10 feet (3 meters) in length, with serrated teeth and venom glands, this reptile is the top land predator on the handful of Indonesian islands where it lives. Are you ready to venture into its territory and discover more about this extraordinary animal?
King of the lizards
The Komodo dragon (Varanus komodoensis) is the largest living lizard on Earth. The biggest males can exceed 10 feet (3 meters) in length and weigh close to 200 pounds (90 kilograms) in the wild.
Its body is robust and muscular, supported by powerful legs ending in long, curved claws. It uses them to dig burrows, hold onto prey and defend itself. Its tail, which can be almost as long as the rest of its body, helps it keep its balance, defend itself and propel itself through the water.
Its skin is covered in hardened scales that conceal tiny bones called osteoderms. This natural armor provides particular protection to adult dragons.
The giant lizard has around 60 teeth with serrated edges that resemble those of sharks. They work like biological knives, capable of cutting and tearing flesh. Its teeth are also continuously replaced throughout its life.
On either side of its head are external ear openings, equivalent to the outer ears of other animals. However, its most important sense is not hearing, but its highly developed chemical sense of smell.
That tongue isn’t just for tasting — it’s a chemical detector, picking up scents and helping the dragon track down food from miles away. Image via Bob Brewer/ Unsplash.
A forked tongue
When you see a Komodo dragon constantly flicking its tongue, it isn’t threatening you or showing aggression. It’s “smelling.”
Its forked tongue collects chemical particles from the air and carries them to the Jacobson’s organ, located in the roof of its mouth. The two tips of the tongue can gather information from either side independently, helping the dragon determine where a scent is coming from and follow its trail. Thanks to this system, it can locate food several miles away when conditions are favorable.
In other words, a Komodo dragon doesn’t need to see its prey to find it: it can follow its chemical trail until it reaches it.
Powerful claws, a tongue that can track a scent and venom glands — all packed into one giant lizard. Image via David Clode/ Unsplash.
A bite with a twist
Komodo dragons are predators capable of taking down animals much larger than themselves, including deer, wild boar and water buffalo.
Once it gets a bite on its prey, its serrated teeth sink into the flesh. It then pulls backward with its head and neck, using its body weight to make its teeth slice through the tissue and tear away large chunks of flesh. It doesn’t need an exceptionally powerful bite: it is the combination of its teeth, powerful neck and that pulling motion that makes its bite so effective.
And it has another weapon. Komodo dragons have venom glands in their lower jaws. Their venom promotes bleeding and interferes with blood clotting, allowing the prey to lose blood and weaken rapidly.
Serrated teeth, a powerful neck and an impressive feeding technique allow this giant lizard to tackle surprisingly large prey. Image via Rasmus Gundorff Saederup/ Unsplash.
Nothing goes to waste
Although they are formidable hunters, they never pass up an opportunity for a meal. Carrion can make up a significant part of their diet, and when they find a carcass, they make use of almost everything, including bones that other animals would leave behind.
Their diet is remarkably varied. They can eat large mammals, birds, eggs, other reptiles and even other Komodo dragons! Yes, really …
Nothing is off the menu … even other Komodo dragons. Image via Dennis Schmidt/ Unsplash.
A very different childhood
Being born a Komodo dragon doesn’t guarantee a long life. Although they can live for more than 30 years, the first few years of life are particularly challenging.
Young dragons spend much of their early lives taking refuge in trees. This offers them some protection from adults, which practice cannibalism and will readily eat smaller individuals when the opportunity arises.
This constant threat forces young dragons to live very differently from adults. While adults roam the ground, young dragons remain among the branches, feeding on smaller prey and keeping out of the adults’ reach.
For a young Komodo dragon, the safest place is up in the trees — far from hungry adults. Image via Timon Cornelissen/ Pexels.
Island navigators
At first glance, an animal this heavy doesn’t exactly look like a great swimmer. Yet Komodo dragons can travel through the sea and cross short stretches of water between islands.
The tail provides much of the propulsion, while the feet, whose toes are partially joined by webbing, help with maneuvering in the water. This ability is particularly important in an archipelago where populations do not always remain completely isolated.
The occasional movement of individuals between islands promotes genetic exchange and reduces some of the risks associated with small, isolated populations.
Watch a Komodo dragon swim.
A reptile full of surprises
Like all reptiles, Komodo dragons are ectothermic: they rely on heat from their surroundings to regulate their body temperature. As a result, they alternate between periods of activity and periods of resting in the sun or shade.
Interestingly, they grow slowly and reach sexual maturity relatively late, usually between eight and ten years of age.
But perhaps the most surprising feature is their ability to reproduce through parthenogenesis. Like most animals, Komodo dragons normally reproduce sexually. However, females can also produce viable eggs without being fertilized by a male.
This ability was discovered in zoos when isolated females produced offspring despite having had no contact with males. For a species spread across several islands, this strategy could be useful if a female reached a new territory on her own and could not find a mate.
But parthenogenesis comes with a trade-off: the offspring produced this way are always male. That means these males would have to mate with their mother to continue the family line, unless they came across other unrelated Komodo dragons.
So while this ability could give a lone female a remarkable advantage in establishing a population in a new territory, it could also limit genetic diversity in that population, which can be harmful.
No male? No problem. A female Komodo dragon can produce offspring on her own. Image via Dimitri Dim/ Pexels.
Busting myths
There are many misconceptions surrounding the Komodo dragon. Let’s bust some myths!
“They kill with the bacteria in their saliva.”
Their saliva does contain bacteria, but the current scientific understanding considers the venom and the wounds caused by the bite to play the main role in their hunting.
“They have the strongest bite of any animal.”
Despite their size and powerful jaws, their hunting success does not depend on exceptional bite force.
“They change color like chameleons.”
There is no solid evidence that Komodo dragons deliberately change color according to the season, their surroundings, or their mood. There is, however, natural variation in coloration between individuals and populations.
“They hunt in packs.”
They are normally solitary animals. When several individuals gather together, it is usually because there is carrion or another abundant food source.
“They became giant because they live on islands.”
The Komodo dragon does live on islands, but its enormous size did not suddenly appear when its ancestors became isolated. Its ancestors already belonged to a group of large lizards. During its evolution, island isolation may have favored the maintenance and even the increase of that size. As it became one of the main terrestrial predators in its ecosystem, a large body allowed it to tackle larger prey and compete more successfully for resources. Today, the Komodo dragon is the largest lizard on Earth.
There’s more to this giant lizard than meets the eye. Its strangest tricks are hidden beneath that prehistoric appearance. Image via M. Rosyadi Aulawi/ Unsplash.
The dragon of Indonesia
The Komodo dragon is naturally found on only a handful of Indonesian islands, including Komodo, Rinca, Flores and Gili Motang.
Habitat loss, declining prey populations and the effects of climate change pose significant challenges to its future survival.
This impressive animal is one of Indonesia’s greatest natural symbols and an emblem of an archipelago that’s home to some of the most extraordinary species on the planet.
For thousands of years, these islands have provided the Komodo dragon with the conditions it needs to survive. The challenge now is to preserve that balance so it can continue to do so for many years to come.
For all its size, the Komodo dragon has an incredibly small home range: just a handful of islands in Indonesia. There is nowhere else on Earth where you can find a giant lizard quite like this one. Image via Jeffry Surianto/ Pexels.
Bottom line: The Komodo dragon is the world’s largest lizard. It’s a venomous predator that can hunt, swim between islands and reproduce without a mate.
More than 10 feet (3 meters) of muscle, armor, claws and serrated teeth … Now that’s a lizard! Image via Mikhaël Noury/ Pexels.
Let me introduce you to the Komodo dragon, the largest lizard in the world. It can detect food from miles away, hunt large mammals, swim between islands and even produce offspring without a male. Impressive, right? Looking at its size, claws, teeth and prehistoric appearance, the name “dragon” seems pretty fitting.
Growing to more than 10 feet (3 meters) in length, with serrated teeth and venom glands, this reptile is the top land predator on the handful of Indonesian islands where it lives. Are you ready to venture into its territory and discover more about this extraordinary animal?
King of the lizards
The Komodo dragon (Varanus komodoensis) is the largest living lizard on Earth. The biggest males can exceed 10 feet (3 meters) in length and weigh close to 200 pounds (90 kilograms) in the wild.
Its body is robust and muscular, supported by powerful legs ending in long, curved claws. It uses them to dig burrows, hold onto prey and defend itself. Its tail, which can be almost as long as the rest of its body, helps it keep its balance, defend itself and propel itself through the water.
Its skin is covered in hardened scales that conceal tiny bones called osteoderms. This natural armor provides particular protection to adult dragons.
The giant lizard has around 60 teeth with serrated edges that resemble those of sharks. They work like biological knives, capable of cutting and tearing flesh. Its teeth are also continuously replaced throughout its life.
On either side of its head are external ear openings, equivalent to the outer ears of other animals. However, its most important sense is not hearing, but its highly developed chemical sense of smell.
That tongue isn’t just for tasting — it’s a chemical detector, picking up scents and helping the dragon track down food from miles away. Image via Bob Brewer/ Unsplash.
A forked tongue
When you see a Komodo dragon constantly flicking its tongue, it isn’t threatening you or showing aggression. It’s “smelling.”
Its forked tongue collects chemical particles from the air and carries them to the Jacobson’s organ, located in the roof of its mouth. The two tips of the tongue can gather information from either side independently, helping the dragon determine where a scent is coming from and follow its trail. Thanks to this system, it can locate food several miles away when conditions are favorable.
In other words, a Komodo dragon doesn’t need to see its prey to find it: it can follow its chemical trail until it reaches it.
Powerful claws, a tongue that can track a scent and venom glands — all packed into one giant lizard. Image via David Clode/ Unsplash.
A bite with a twist
Komodo dragons are predators capable of taking down animals much larger than themselves, including deer, wild boar and water buffalo.
Once it gets a bite on its prey, its serrated teeth sink into the flesh. It then pulls backward with its head and neck, using its body weight to make its teeth slice through the tissue and tear away large chunks of flesh. It doesn’t need an exceptionally powerful bite: it is the combination of its teeth, powerful neck and that pulling motion that makes its bite so effective.
And it has another weapon. Komodo dragons have venom glands in their lower jaws. Their venom promotes bleeding and interferes with blood clotting, allowing the prey to lose blood and weaken rapidly.
Serrated teeth, a powerful neck and an impressive feeding technique allow this giant lizard to tackle surprisingly large prey. Image via Rasmus Gundorff Saederup/ Unsplash.
Nothing goes to waste
Although they are formidable hunters, they never pass up an opportunity for a meal. Carrion can make up a significant part of their diet, and when they find a carcass, they make use of almost everything, including bones that other animals would leave behind.
Their diet is remarkably varied. They can eat large mammals, birds, eggs, other reptiles and even other Komodo dragons! Yes, really …
Nothing is off the menu … even other Komodo dragons. Image via Dennis Schmidt/ Unsplash.
A very different childhood
Being born a Komodo dragon doesn’t guarantee a long life. Although they can live for more than 30 years, the first few years of life are particularly challenging.
Young dragons spend much of their early lives taking refuge in trees. This offers them some protection from adults, which practice cannibalism and will readily eat smaller individuals when the opportunity arises.
This constant threat forces young dragons to live very differently from adults. While adults roam the ground, young dragons remain among the branches, feeding on smaller prey and keeping out of the adults’ reach.
For a young Komodo dragon, the safest place is up in the trees — far from hungry adults. Image via Timon Cornelissen/ Pexels.
Island navigators
At first glance, an animal this heavy doesn’t exactly look like a great swimmer. Yet Komodo dragons can travel through the sea and cross short stretches of water between islands.
The tail provides much of the propulsion, while the feet, whose toes are partially joined by webbing, help with maneuvering in the water. This ability is particularly important in an archipelago where populations do not always remain completely isolated.
The occasional movement of individuals between islands promotes genetic exchange and reduces some of the risks associated with small, isolated populations.
Watch a Komodo dragon swim.
A reptile full of surprises
Like all reptiles, Komodo dragons are ectothermic: they rely on heat from their surroundings to regulate their body temperature. As a result, they alternate between periods of activity and periods of resting in the sun or shade.
Interestingly, they grow slowly and reach sexual maturity relatively late, usually between eight and ten years of age.
But perhaps the most surprising feature is their ability to reproduce through parthenogenesis. Like most animals, Komodo dragons normally reproduce sexually. However, females can also produce viable eggs without being fertilized by a male.
This ability was discovered in zoos when isolated females produced offspring despite having had no contact with males. For a species spread across several islands, this strategy could be useful if a female reached a new territory on her own and could not find a mate.
But parthenogenesis comes with a trade-off: the offspring produced this way are always male. That means these males would have to mate with their mother to continue the family line, unless they came across other unrelated Komodo dragons.
So while this ability could give a lone female a remarkable advantage in establishing a population in a new territory, it could also limit genetic diversity in that population, which can be harmful.
No male? No problem. A female Komodo dragon can produce offspring on her own. Image via Dimitri Dim/ Pexels.
Busting myths
There are many misconceptions surrounding the Komodo dragon. Let’s bust some myths!
“They kill with the bacteria in their saliva.”
Their saliva does contain bacteria, but the current scientific understanding considers the venom and the wounds caused by the bite to play the main role in their hunting.
“They have the strongest bite of any animal.”
Despite their size and powerful jaws, their hunting success does not depend on exceptional bite force.
“They change color like chameleons.”
There is no solid evidence that Komodo dragons deliberately change color according to the season, their surroundings, or their mood. There is, however, natural variation in coloration between individuals and populations.
“They hunt in packs.”
They are normally solitary animals. When several individuals gather together, it is usually because there is carrion or another abundant food source.
“They became giant because they live on islands.”
The Komodo dragon does live on islands, but its enormous size did not suddenly appear when its ancestors became isolated. Its ancestors already belonged to a group of large lizards. During its evolution, island isolation may have favored the maintenance and even the increase of that size. As it became one of the main terrestrial predators in its ecosystem, a large body allowed it to tackle larger prey and compete more successfully for resources. Today, the Komodo dragon is the largest lizard on Earth.
There’s more to this giant lizard than meets the eye. Its strangest tricks are hidden beneath that prehistoric appearance. Image via M. Rosyadi Aulawi/ Unsplash.
The dragon of Indonesia
The Komodo dragon is naturally found on only a handful of Indonesian islands, including Komodo, Rinca, Flores and Gili Motang.
Habitat loss, declining prey populations and the effects of climate change pose significant challenges to its future survival.
This impressive animal is one of Indonesia’s greatest natural symbols and an emblem of an archipelago that’s home to some of the most extraordinary species on the planet.
For thousands of years, these islands have provided the Komodo dragon with the conditions it needs to survive. The challenge now is to preserve that balance so it can continue to do so for many years to come.
For all its size, the Komodo dragon has an incredibly small home range: just a handful of islands in Indonesia. There is nowhere else on Earth where you can find a giant lizard quite like this one. Image via Jeffry Surianto/ Pexels.
Bottom line: The Komodo dragon is the world’s largest lizard. It’s a venomous predator that can hunt, swim between islands and reproduce without a mate.
What is a Harvest Moon? Plus, how can you see this 2026 Harvest Moon near Saturn? EarthSky’s Deborah Byrd has more. Watch in the player above or on YouTube.
When and where to look in 2026: Look for the bright, round full moon climbing in the east at sunset on September 26, glowing in the south near midnight, and dropping low in the west just before sunrise on September 27. It’s the full moon closest to the equinox: the Harvest Moon. Crest of the full moon will fall at 16:49 UTC on September 26. That’s 11:49 a.m. CDT.
The 2026 Harvest Moon will lie near golden Saturn. Saturn’s opposition – when it will be opposite the sun from Earth – will fall on October 4. A full moon is always opposite the sun. And Saturn is near opposition, but still generally opposite the sun now, too. So it makes sense that this full moon and Saturn are close together. Check Stellarium.org for a precise view from your location.
The bright September full moon – the Harvest Moon, or full moon closest to the autumn equinox – will float near Saturn in the sky around the nights of September 24 to 28. Chart via EarthSky.
What’s a Harvest Moon?
Harvest Moon isn’t just a name. It denotes a time of year when the full moon – as seen from the Northern Hemisphere – has special characteristics.
We in the Northern Hemisphere have long called the full moon closest to the September equinox by the name Harvest Moon. That name – Harvest Moon – might be the best known full moon name of the year. This year, the September equinox occurs at 0:05 UTC on September 23, 2026. That’s 9:05 p.m. CDT on September 22. The full moon falls about three days later.
At full moon, the sun, Earth and moon are aligned with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.View at EarthSky Community Photos. | Marsha Chan in Los Angeles, California, captured this celestial trifecta – of the Harvest Moon, a supermoon and a partial lunar eclipse – on September 17, 2024. Thank you, Marsha!
How did the Harvest Moon get its name?
The shorter-than-usual lag time between moonrises around the full Harvest Moon means no long period of darkness between sunset and moonrise for days in succession.
The difference between 50 minutes and 25 minutes might not seem like much. But it means that, in the nights after a full Harvest Moon, you’ll see the moon ascending in the east relatively soon after sunset. The moon will rise during or near deepening twilight on these nights, presenting dusk-till-dawn moonlight for several nights in a row around the time of the Harvest Moon.
In the days before tractor lights, the lamp of the Harvest Moon helped farmers gather their crops despite the diminishing daylight hours. As the sun’s light faded in the west, the moon would soon rise in the east to illuminate the fields throughout the night.
Who named the Harvest Moon? That name probably sprang to the lips of farmers throughout the Northern Hemisphere, on autumn evenings, as the Harvest Moon aided in bringing in the crops.
By the way, for very high northern latitudes, there’s even less time between successive moonrises. The farther north you live, the greater the Harvest Moon effect. For instance, at Anchorage, Alaska (61 degrees north latitude), the moon will rise at nearly the same time for a week!
Is the Harvest Moon bigger, brighter or more colorful?
Because the moon’s orbit around Earth isn’t a perfect circle, the Harvest Moon’s distance from Earth – and apparent size in our sky – differs from year to year. In 2019, the Harvest Moon was actually a micromoon or mini-moon: the most distant and smallest full moon of that year. And – in 2015 – the Harvest Moon was the year’s closest and biggest supermoon of the year.
In 2024, the Harvest Moon was a full supermoon, but not the closest supermoon for the year. There was also a partial lunar eclipse.
So, the full Harvest Moon isn’t necessarily closer than any other full moon. But it might be. The moon’s distance at full moon varies from year to year.
It looks bigger, but isn’t
Still, in any year, you might think the Harvest Moon looks bigger, brighter or more orange. That’s because the Harvest Moon has such a powerful mystique. Many people look for it shortly after sunset around the time of full moon. After sunset around the time of any full moon, the moon will always be near the horizon. It’ll have just risen. It’s the location of the moon near the horizon that causes the Harvest Moon – or any full moon – to look big and orange in color.
A big moon seen near the horizon presents you with a psychological effect. It’s a trick your eyes are playing – an illusion – called the moon illusion. You can find many lengthy explanations of the moon illusion by doing an online search for those words.
View at EarthSky Community Photos. | Kannan A captured this image on September 21, 2021, and wrote: “The Harvest Moon seen in Singapore about 1 hour after it had risen from the east. Cropped the picture to show the upper section of the moon. The moon was very bright and coincided with the Mooncake or Lantern Festival in Singapore. The moon maria were clearly visible, from the top Mare Crisium, to the bottom. Beginning from the left of this photo is Mare Imbrium, Mare Serenitatis (Apollo 17 landing site), Mare Tranquillitatis (Apollo 11 landing site) and Mare Fecunditatis.” Thank you, Kannan A!
Orange color due to thickness of Earth’s atmosphere near horizon
By the way, the orange color of a moon near the horizon isn’t a psychological effect. It’s a true physical effect, which stems from the fact that – when you look toward a horizon – you’re looking through a greater thickness of Earth’s atmosphere than when you gaze up and overhead.
View at EarthSky Community Photos. | Kent Kirkley of Dallas, Texas, captured this image on September 9, 2022, and wrote: “September Harvest Full Moon rise.” Thank you, Kent!
September full moon lies in Pisces and near Saturn
The September Harvest full moon always lies in front of one of three constellations of the zodiac. Most years, it lies in Pisces the Fish, as it does this year. About every three years, though, it’ll lie in Aquarius the Water Bearer. Very infrequently – once about every 20 years – it’ll fall in the less-familiar constellation lying to their south, Cetus the Whale.
The September 2026 full moon occurs on the overnight of September 26 and lies in the constellation Pisces. Chart via EarthSky.
September full moon and the ecliptic
Why? It’s because the ecliptic – or path of the sun, moon and planets across our sky – makes a narrow angle with the eastern horizon near sunset, around the time of the autumn equinox. For Northern Hemisphere observers, that means September or October. For Southern Hemisphere observers, it means March or April. The narrow angle of the ecliptic to the evening horizon – around the time of the autumn equinox – gives us the short interval between successive moonrises and the Harvest Moon.
And a short interval between successive moonrises means that – for several evenings in a row, around the time of this September full moon – you’ll find a full or nearly full-looking moon low in the east in evening twilight. Before the days of electric lights, the early evening light of this full moon let farmers working in the fields have more time to work, before darkness settled. Hence the name Harvest Moon.
And, by the way, for the Southern Hemisphere at this full moon, there’s a particularly long interval between successive moonrises!
Bottom line: The September Harvest Full Moon happens on September 26, 2026. This full moon lies in front of the constellation Pisces. And it lies near the golden planet Saturn.
What is a Harvest Moon? Plus, how can you see this 2026 Harvest Moon near Saturn? EarthSky’s Deborah Byrd has more. Watch in the player above or on YouTube.
When and where to look in 2026: Look for the bright, round full moon climbing in the east at sunset on September 26, glowing in the south near midnight, and dropping low in the west just before sunrise on September 27. It’s the full moon closest to the equinox: the Harvest Moon. Crest of the full moon will fall at 16:49 UTC on September 26. That’s 11:49 a.m. CDT.
The 2026 Harvest Moon will lie near golden Saturn. Saturn’s opposition – when it will be opposite the sun from Earth – will fall on October 4. A full moon is always opposite the sun. And Saturn is near opposition, but still generally opposite the sun now, too. So it makes sense that this full moon and Saturn are close together. Check Stellarium.org for a precise view from your location.
The bright September full moon – the Harvest Moon, or full moon closest to the autumn equinox – will float near Saturn in the sky around the nights of September 24 to 28. Chart via EarthSky.
What’s a Harvest Moon?
Harvest Moon isn’t just a name. It denotes a time of year when the full moon – as seen from the Northern Hemisphere – has special characteristics.
We in the Northern Hemisphere have long called the full moon closest to the September equinox by the name Harvest Moon. That name – Harvest Moon – might be the best known full moon name of the year. This year, the September equinox occurs at 0:05 UTC on September 23, 2026. That’s 9:05 p.m. CDT on September 22. The full moon falls about three days later.
At full moon, the sun, Earth and moon are aligned with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.View at EarthSky Community Photos. | Marsha Chan in Los Angeles, California, captured this celestial trifecta – of the Harvest Moon, a supermoon and a partial lunar eclipse – on September 17, 2024. Thank you, Marsha!
How did the Harvest Moon get its name?
The shorter-than-usual lag time between moonrises around the full Harvest Moon means no long period of darkness between sunset and moonrise for days in succession.
The difference between 50 minutes and 25 minutes might not seem like much. But it means that, in the nights after a full Harvest Moon, you’ll see the moon ascending in the east relatively soon after sunset. The moon will rise during or near deepening twilight on these nights, presenting dusk-till-dawn moonlight for several nights in a row around the time of the Harvest Moon.
In the days before tractor lights, the lamp of the Harvest Moon helped farmers gather their crops despite the diminishing daylight hours. As the sun’s light faded in the west, the moon would soon rise in the east to illuminate the fields throughout the night.
Who named the Harvest Moon? That name probably sprang to the lips of farmers throughout the Northern Hemisphere, on autumn evenings, as the Harvest Moon aided in bringing in the crops.
By the way, for very high northern latitudes, there’s even less time between successive moonrises. The farther north you live, the greater the Harvest Moon effect. For instance, at Anchorage, Alaska (61 degrees north latitude), the moon will rise at nearly the same time for a week!
Is the Harvest Moon bigger, brighter or more colorful?
Because the moon’s orbit around Earth isn’t a perfect circle, the Harvest Moon’s distance from Earth – and apparent size in our sky – differs from year to year. In 2019, the Harvest Moon was actually a micromoon or mini-moon: the most distant and smallest full moon of that year. And – in 2015 – the Harvest Moon was the year’s closest and biggest supermoon of the year.
In 2024, the Harvest Moon was a full supermoon, but not the closest supermoon for the year. There was also a partial lunar eclipse.
So, the full Harvest Moon isn’t necessarily closer than any other full moon. But it might be. The moon’s distance at full moon varies from year to year.
It looks bigger, but isn’t
Still, in any year, you might think the Harvest Moon looks bigger, brighter or more orange. That’s because the Harvest Moon has such a powerful mystique. Many people look for it shortly after sunset around the time of full moon. After sunset around the time of any full moon, the moon will always be near the horizon. It’ll have just risen. It’s the location of the moon near the horizon that causes the Harvest Moon – or any full moon – to look big and orange in color.
A big moon seen near the horizon presents you with a psychological effect. It’s a trick your eyes are playing – an illusion – called the moon illusion. You can find many lengthy explanations of the moon illusion by doing an online search for those words.
View at EarthSky Community Photos. | Kannan A captured this image on September 21, 2021, and wrote: “The Harvest Moon seen in Singapore about 1 hour after it had risen from the east. Cropped the picture to show the upper section of the moon. The moon was very bright and coincided with the Mooncake or Lantern Festival in Singapore. The moon maria were clearly visible, from the top Mare Crisium, to the bottom. Beginning from the left of this photo is Mare Imbrium, Mare Serenitatis (Apollo 17 landing site), Mare Tranquillitatis (Apollo 11 landing site) and Mare Fecunditatis.” Thank you, Kannan A!
Orange color due to thickness of Earth’s atmosphere near horizon
By the way, the orange color of a moon near the horizon isn’t a psychological effect. It’s a true physical effect, which stems from the fact that – when you look toward a horizon – you’re looking through a greater thickness of Earth’s atmosphere than when you gaze up and overhead.
View at EarthSky Community Photos. | Kent Kirkley of Dallas, Texas, captured this image on September 9, 2022, and wrote: “September Harvest Full Moon rise.” Thank you, Kent!
September full moon lies in Pisces and near Saturn
The September Harvest full moon always lies in front of one of three constellations of the zodiac. Most years, it lies in Pisces the Fish, as it does this year. About every three years, though, it’ll lie in Aquarius the Water Bearer. Very infrequently – once about every 20 years – it’ll fall in the less-familiar constellation lying to their south, Cetus the Whale.
The September 2026 full moon occurs on the overnight of September 26 and lies in the constellation Pisces. Chart via EarthSky.
September full moon and the ecliptic
Why? It’s because the ecliptic – or path of the sun, moon and planets across our sky – makes a narrow angle with the eastern horizon near sunset, around the time of the autumn equinox. For Northern Hemisphere observers, that means September or October. For Southern Hemisphere observers, it means March or April. The narrow angle of the ecliptic to the evening horizon – around the time of the autumn equinox – gives us the short interval between successive moonrises and the Harvest Moon.
And a short interval between successive moonrises means that – for several evenings in a row, around the time of this September full moon – you’ll find a full or nearly full-looking moon low in the east in evening twilight. Before the days of electric lights, the early evening light of this full moon let farmers working in the fields have more time to work, before darkness settled. Hence the name Harvest Moon.
And, by the way, for the Southern Hemisphere at this full moon, there’s a particularly long interval between successive moonrises!
Bottom line: The September Harvest Full Moon happens on September 26, 2026. This full moon lies in front of the constellation Pisces. And it lies near the golden planet Saturn.
View at EarthSky Community Photos. | Our friend Cecille Kennedy captured the waning gibbous moon in the early morning of November 7, 2025, from the Oregon Coast. Cecille wrote: “At moonset … the waning gibbous moon in the western sky with sunrise hues, two days after the full moon.” Thank you, Cecille! Find out more about the daytime moon below.
Watch for the daytime moon
The moon is up in the daytime half of the time. But, because it’s pale against the blue sky, it’s not as noticeable during the day as at night. Still, there are certain windows each month during which the daytime moon is most noticeable.
The coming week presents one of those windows. It’s a good time to watch for a daytime moon in the morning sky. The full Harvest Moon was yesterday (September 26, 2026). So — in the week ahead — you’ll find the moon in a waning gibbous phase, appearing more than half lighted but less than full. Full moons rise at sunset. But waning gibbous moons rise later – and later – on each successive night.
And that means the moon sets later and later now, too. In the days following every full moon, you’ll find the moon setting in the west after sunrise. That makes the mornings following a full moon a good time to catch a daytime moon. Watch for it during the coming week, after sunrise, over your western horizon. It’ll appear pale against the blue sky.
Thanks to what’s called the moon illusion, you might notice the daytime moon looking huge when close to the horizon.
When is last quarter moon?
And the moon will continue to wane. The last quarter moon — where the moon presented exactly half of its “day” or illuminated side to Earth — will fall at 13:25 UTC on October 3, 2026. Last quarter moons rise in the middle of the night (no matter where you are on the globe). And they set around midday. Watch for the last quarter moon high in the sky before dawn.
Daytime moon photos from the EarthSky community
View at EarthSky Community Photos. | Mandy Daniels captured the waning gibbous moon in daylight on August 5, 2026, in the UK. Thank you, Mandy!EarthSky’s Marcy Curran captured the waning gibbous moon before it slipped behind some clouds on the morning of September 4, 2026. Thank you, Marcy!View at EarthSky Community Photos. | Mandy Daniels captured this image of the 1st quarter moon on February 24, 2026, from the UK. Thank you, Mandy! The 1st quarter moon rises at noon and sets at midnight. So watch for it high in the eastern sky mid-afternoon.
Bottom line: Watch for the beautiful daytime moon this week, a pale orb floating against a blue sky in the morning hours. Look west! You’ll see it!
View at EarthSky Community Photos. | Our friend Cecille Kennedy captured the waning gibbous moon in the early morning of November 7, 2025, from the Oregon Coast. Cecille wrote: “At moonset … the waning gibbous moon in the western sky with sunrise hues, two days after the full moon.” Thank you, Cecille! Find out more about the daytime moon below.
Watch for the daytime moon
The moon is up in the daytime half of the time. But, because it’s pale against the blue sky, it’s not as noticeable during the day as at night. Still, there are certain windows each month during which the daytime moon is most noticeable.
The coming week presents one of those windows. It’s a good time to watch for a daytime moon in the morning sky. The full Harvest Moon was yesterday (September 26, 2026). So — in the week ahead — you’ll find the moon in a waning gibbous phase, appearing more than half lighted but less than full. Full moons rise at sunset. But waning gibbous moons rise later – and later – on each successive night.
And that means the moon sets later and later now, too. In the days following every full moon, you’ll find the moon setting in the west after sunrise. That makes the mornings following a full moon a good time to catch a daytime moon. Watch for it during the coming week, after sunrise, over your western horizon. It’ll appear pale against the blue sky.
Thanks to what’s called the moon illusion, you might notice the daytime moon looking huge when close to the horizon.
When is last quarter moon?
And the moon will continue to wane. The last quarter moon — where the moon presented exactly half of its “day” or illuminated side to Earth — will fall at 13:25 UTC on October 3, 2026. Last quarter moons rise in the middle of the night (no matter where you are on the globe). And they set around midday. Watch for the last quarter moon high in the sky before dawn.
Daytime moon photos from the EarthSky community
View at EarthSky Community Photos. | Mandy Daniels captured the waning gibbous moon in daylight on August 5, 2026, in the UK. Thank you, Mandy!EarthSky’s Marcy Curran captured the waning gibbous moon before it slipped behind some clouds on the morning of September 4, 2026. Thank you, Marcy!View at EarthSky Community Photos. | Mandy Daniels captured this image of the 1st quarter moon on February 24, 2026, from the UK. Thank you, Mandy! The 1st quarter moon rises at noon and sets at midnight. So watch for it high in the eastern sky mid-afternoon.
Bottom line: Watch for the beautiful daytime moon this week, a pale orb floating against a blue sky in the morning hours. Look west! You’ll see it!
Here’s astronaut Christina Koch looking back at Earth, out the window of the Orion spacecraft – aka Integrity – on its way to the moon during the Artemis 2 mission. The Artemis Accords — a set of guidelines for the exploration of space, with a focus on the moon — are named after the Artemis program. Image via NASA.
In 2020, NASA and the U.S. Department of State led an effort to establish guidelines for human expansion into space. Working with international partners, they came up with the Artemis Accords. NASA describes the accords as:
… a common set of principles to enhance the governance of the civil exploration and use of outer space.
As of late September 2026, 74 countries have signed the Artemis Accords. There are some notable exceptions, including Russia and China.
While the rules are for space in general, they are largely focused on humans’ expansion onto the moon. Thus, they are named for NASA’s Artemis program, which currently aims to have humans standing on the moon again in early 2028.
What are the Artemis Accords?
The Artemis Accords are a set of nonbinding principles for how countries should cooperate in space. The accords build on the 1967 Outer Space Treaty. NASA focuses on a number of key areas, including:
peaceful purposes
transparency
interoperability
emergency assistance
registration of space objects
release of scientific data
preserving outer space heritage
space resources
deconfliction of space activities
orbital debris
So, for example, the accords call for protecting historic sites such as the Apollo landing sites. They also support the use of space resources, such as lunar water or asteroid materials, provided those activities comply with international law.
Humanity suddenly has many plans for expanding into space. And it’s not just countries, but private companies with plans as well. So the intention here is to make space safer and more cooperative.
For example, if two nations are operating in the same area of the moon, the accords call for them to share information and coordinate their activities to avoid harmful interference. Temporary safety zones can help accomplish that without claiming ownership of lunar territory.
The accords don’t replace the Outer Space Treaty or create a new international space law. Instead, they just provide a common framework for putting responsible practices into action. As NASA puts it, the goal is a “safe, peaceful and prosperous future in space.”
The Artemis Accords are a set of guidelines for exploration of space with a focus on the moon. NASA named the accords after its Artemis program, which seeks to return people to the moon’s surface and establish a base. Image via NASA.
Questions surrounding the Artemis Accords
There are criticisms and questions surrounding the Artemis Accords. For one, the accords aren’t a binding law but set of agreements. Plus, the Artemis Accords don’t regulate private companies directly. As in, no private companies are signing the accords. Instead, countries sign the accords and are responsible for ensuring that companies operating under their jurisdiction follow the rules.
So, who gets to make the rules for space? The United States is doing much of the steering on the accords. But should it be an international organization, such as the United Nations? The UN Committee on the Peaceful Uses of Outer Space is already working on possible international principles governing space-resource activities. Some delegations at the United Nations have argued that developing countries should not be left behind or excluded from the benefits of space exploration.
A second question is on who gets access to valuable lunar resources. How should those resources be governed? The UN discussions have included calls for rules addressing issues such as sustainability, access, benefit sharing and the rights of countries without the ability to conduct space-resource missions themselves.
Finally, there is the idea of safety zones. The accords allow temporary zones around lunar operations to prevent interference. But the Outer Space Treaty says no country can claim sovereignty over the moon or appropriate it through occupation or use. And couldn’t some countries make a temporary zone that eventually functions like a territorial claim?
While some framework for cooperation in space is necessary, it seems hammering out the details will be a debate for years to come.
The Shackleton crater on the moon with an elevation analysis (left) and shaded relief (right). This 12.5-mile-diameter (21-km-diameter) crater near the south pole is in permanent shadow. Image via NASA.
Bottom line: The Artemis Accords are a set guidelines for peaceful space exploration. But questions remain about who makes the rules and controls space resources.
Here’s astronaut Christina Koch looking back at Earth, out the window of the Orion spacecraft – aka Integrity – on its way to the moon during the Artemis 2 mission. The Artemis Accords — a set of guidelines for the exploration of space, with a focus on the moon — are named after the Artemis program. Image via NASA.
In 2020, NASA and the U.S. Department of State led an effort to establish guidelines for human expansion into space. Working with international partners, they came up with the Artemis Accords. NASA describes the accords as:
… a common set of principles to enhance the governance of the civil exploration and use of outer space.
As of late September 2026, 74 countries have signed the Artemis Accords. There are some notable exceptions, including Russia and China.
While the rules are for space in general, they are largely focused on humans’ expansion onto the moon. Thus, they are named for NASA’s Artemis program, which currently aims to have humans standing on the moon again in early 2028.
What are the Artemis Accords?
The Artemis Accords are a set of nonbinding principles for how countries should cooperate in space. The accords build on the 1967 Outer Space Treaty. NASA focuses on a number of key areas, including:
peaceful purposes
transparency
interoperability
emergency assistance
registration of space objects
release of scientific data
preserving outer space heritage
space resources
deconfliction of space activities
orbital debris
So, for example, the accords call for protecting historic sites such as the Apollo landing sites. They also support the use of space resources, such as lunar water or asteroid materials, provided those activities comply with international law.
Humanity suddenly has many plans for expanding into space. And it’s not just countries, but private companies with plans as well. So the intention here is to make space safer and more cooperative.
For example, if two nations are operating in the same area of the moon, the accords call for them to share information and coordinate their activities to avoid harmful interference. Temporary safety zones can help accomplish that without claiming ownership of lunar territory.
The accords don’t replace the Outer Space Treaty or create a new international space law. Instead, they just provide a common framework for putting responsible practices into action. As NASA puts it, the goal is a “safe, peaceful and prosperous future in space.”
The Artemis Accords are a set of guidelines for exploration of space with a focus on the moon. NASA named the accords after its Artemis program, which seeks to return people to the moon’s surface and establish a base. Image via NASA.
Questions surrounding the Artemis Accords
There are criticisms and questions surrounding the Artemis Accords. For one, the accords aren’t a binding law but set of agreements. Plus, the Artemis Accords don’t regulate private companies directly. As in, no private companies are signing the accords. Instead, countries sign the accords and are responsible for ensuring that companies operating under their jurisdiction follow the rules.
So, who gets to make the rules for space? The United States is doing much of the steering on the accords. But should it be an international organization, such as the United Nations? The UN Committee on the Peaceful Uses of Outer Space is already working on possible international principles governing space-resource activities. Some delegations at the United Nations have argued that developing countries should not be left behind or excluded from the benefits of space exploration.
A second question is on who gets access to valuable lunar resources. How should those resources be governed? The UN discussions have included calls for rules addressing issues such as sustainability, access, benefit sharing and the rights of countries without the ability to conduct space-resource missions themselves.
Finally, there is the idea of safety zones. The accords allow temporary zones around lunar operations to prevent interference. But the Outer Space Treaty says no country can claim sovereignty over the moon or appropriate it through occupation or use. And couldn’t some countries make a temporary zone that eventually functions like a territorial claim?
While some framework for cooperation in space is necessary, it seems hammering out the details will be a debate for years to come.
The Shackleton crater on the moon with an elevation analysis (left) and shaded relief (right). This 12.5-mile-diameter (21-km-diameter) crater near the south pole is in permanent shadow. Image via NASA.
Bottom line: The Artemis Accords are a set guidelines for peaceful space exploration. But questions remain about who makes the rules and controls space resources.
View at EarthSky Community Photos. | Brian Martin in Riverside, California, captured this image on August 19, 2025, and wrote: “I had very nice seeing which afforded me the 2 types of shadows (umbra and penumbra). This is my cleanest Saturn as far as the ring goes where my goal is to keep most of the grey ring in front of the planet and not a bulky black shadow which I believe I achieved well here.” Thank you, Brian! Besides capturing Saturn’s glorious rings, Brian captured the shadow of Titan on Saturn’s surface. Read tips on how to see Saturn’s rings below.
Saturn’s rings are beautiful
Saturn is the most gasp-inducing planet when viewed through a telescope. And it’s currently providing its best views of 2026 as it reaches its October 4 opposition. Saturn looks starlike to the eye alone. It appears as a golden-hued dot and shines steadily, as planets tend to do. Binoculars will enhance its color, and even a small telescope will let you glimpse Saturn’s rings. Veteran observer Alan MacRobert at SkyandTelescope.org has written:
The rings of Saturn should be visible in even the smallest telescope at 25x [magnified by 25 times]. A good 3-inch scope at 50x [magnified by 50 times] can show them as a separate structure detached on all sides from the ball of the planet.
View at EarthSky Community Photos. | Makrem Larnaout of Tunisia captured this image of Saturn on August 6, 2024, and wrote: “I’m excited to share a new image of Saturn, captured with 195 minutes of data using 2 different setups, under average seeing conditions.” Thank you, Makrem!
Attending a star party or astronomy club
Okay, got Saturn? Now … about that telescope. One possibility is to start scouting out a star party near you, where amateur astronomers are set up to show you telescopic objects. For the U.S., check the club map at NASA’s Night Sky Network to find star parties. For clubs outside the U.S., see the list below. You can also call a local university or science museum and ask about star parties. Or maybe a neighbor, or friend, has a telescope stashed in a closet? More possibilities:
Once you can find Saturn in the sky and have a star party to attend, consider the following tips before your ring-viewing session.
View at EarthSky Community Photos. | Steven Bellavia captured this image on September 3, 2026, from Virginia and wrote: “Saturn, with moons Dione, Tethys and Rhea (left-to-right), from 07:30 UTC, September 03, 2026. I may have finally captured the elusive “spokes” which are fuzzy patches on the rings. But it could also be artifacts of capture and processing.” Thank you, Steven!
Tip 1: You need a telescope to see Saturn’s rings
Don’t expect to see the rings in binoculars. You really do need a telescope. A bigger telescope will show you more than a smaller telescope.
Saturn and its rings in 2026. The days around east and west quadrature (when Saturn is located 90 degrees from the sun) are better than opposition for seeing the shadow of or on the rings, and eclipses of the satellites. Image via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.
Tip 2: Consider the tilt of Saturn’s rings
Notice the tilt of the rings. As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical. In 2017, the north side of the rings opened up most widely (27 degrees), as seen from Earth. That’s the most open this side of the rings has been since 1988.
In 2025, the rings appeared edge-on as seen from Earth in March. After that, we began to see the south side of Saturn’s rings, which will gradually increase to a maximum inclination of 27 degrees by May 2032. By the way, they were almost look edge-on again in late November 2025. And around the October 2026 opposition, the rings are titled -7.5 degrees with the southern side of the ring plane exposed.
The tilt of Saturn’s rings has a great impact on the planet’s overall brightness as seen from Earth. In years when Saturn’s rings are edge-on (2009 and 2025), Saturn does appear considerably dimmer. A computer program by Tom Ruen simulated these Saturn views. Image via Wikimedia Commons (GFDL).
Tip 3: Can you see the rings in 3D?
Ask yourself … do Saturn’s rings look three-dimensional? Again quoting Alan MacRobert at SkyandTelescope.org:
Saturn has a more three-dimensional appearance than any other object in the sky; at least that’s how it looks to me with a 6-inch ‘scope on a night of fine seeing.
Shadows cast by the ring on the planet in front and by the planet on the farther ring can make the image of Saturn pop.
Tip 4: How’s the seeing?
What was Alan talking about in that quote above when he mentioned seeing? Both amateur and professional astronomers talk about the night’s seeing, which affects how clearly and sharply you can see a telescopic image. Seeing isn’t a quality of the telescope; it’s a quality of the air above you. It’s the reason the stars twinkle more on some nights than others.
When the air is particularly turbulent, astronomers say there’s bad seeing. The images in the telescope shimmy and dance. When the air is particularly still, astronomers say there’s good seeing. Seeing can shift from moment to moment as parcels of air move above you. So, as you’re gazing at Saturn, stand as quietly as you can – for as long as you can – and just look. You’ll notice moments when the image suddenly comes into sharper focus.
Other tips to consider
Once you get comfortable viewing Saturn – assuming you’re able to view it again and again, with a telescope of your own – you’ll begin to notice details in the rings.
Today, thanks to spacecraft, we know that Saturn’s rings are incredibly detailed. But, as you stand at your telescope gazing upward, you might be thrilled to witness just one primary division in the rings, the Cassini Division between the A and B rings, named for its French discoverer Jean Cassini.
Seeing this dark division is a good test of the night’s seeing and your telescope’s optical quality, and also of your own eyes’ ability to simply look and notice what you see. By the way, if you’re looking at the rings – which means you’re viewing Saturn through a telescope – also look for one or more of Saturn’s many moons, most notably Titan.
The Opposition Surge
A phenomenon that occurs when Saturn is at opposition is that the rings brighten for a few days. You can only see this a few nights on either side of opposition, which this year occurs on October 4.
This is the Seeliger Effect, which Hugo von Seeliger first described more than 100 years ago. Normally the rings appear as bright as the globe of the planet. But as the planet lines up with the Earth and the sun, more sunlight suddenly gets reflected back to us from the rings than from the globe, and the rings take on an additional level of brightness.
The two mechanisms for this brightening are shadow hiding and a coherent reflection of sunlight off the rings’ particles. Shadow hiding occurs because the shadows are the shortest on the ring particles. The coherent reflection of light occurs because light going straight into the ice particles reflects off of the inner surfaces, then straight back to where it came from.
This brightness surge lasts only a few days; see a study showing this increase. The window for this opportunity is the days around October 4.
Have fun!
Alas, you won’t see Saturn looking like this through a telescope. This is a spacecraft view from Cassini in 2016, showing Saturn’s northern hemisphere. Image via NASA/ JPL-Caltech/ Space Science Institute.
Bottom line: If you want to see Saturn’s rings at their best in 2026, late September and early October is a great time to look. Grab a telescope and read the tips found here!
View at EarthSky Community Photos. | Brian Martin in Riverside, California, captured this image on August 19, 2025, and wrote: “I had very nice seeing which afforded me the 2 types of shadows (umbra and penumbra). This is my cleanest Saturn as far as the ring goes where my goal is to keep most of the grey ring in front of the planet and not a bulky black shadow which I believe I achieved well here.” Thank you, Brian! Besides capturing Saturn’s glorious rings, Brian captured the shadow of Titan on Saturn’s surface. Read tips on how to see Saturn’s rings below.
Saturn’s rings are beautiful
Saturn is the most gasp-inducing planet when viewed through a telescope. And it’s currently providing its best views of 2026 as it reaches its October 4 opposition. Saturn looks starlike to the eye alone. It appears as a golden-hued dot and shines steadily, as planets tend to do. Binoculars will enhance its color, and even a small telescope will let you glimpse Saturn’s rings. Veteran observer Alan MacRobert at SkyandTelescope.org has written:
The rings of Saturn should be visible in even the smallest telescope at 25x [magnified by 25 times]. A good 3-inch scope at 50x [magnified by 50 times] can show them as a separate structure detached on all sides from the ball of the planet.
View at EarthSky Community Photos. | Makrem Larnaout of Tunisia captured this image of Saturn on August 6, 2024, and wrote: “I’m excited to share a new image of Saturn, captured with 195 minutes of data using 2 different setups, under average seeing conditions.” Thank you, Makrem!
Attending a star party or astronomy club
Okay, got Saturn? Now … about that telescope. One possibility is to start scouting out a star party near you, where amateur astronomers are set up to show you telescopic objects. For the U.S., check the club map at NASA’s Night Sky Network to find star parties. For clubs outside the U.S., see the list below. You can also call a local university or science museum and ask about star parties. Or maybe a neighbor, or friend, has a telescope stashed in a closet? More possibilities:
Once you can find Saturn in the sky and have a star party to attend, consider the following tips before your ring-viewing session.
View at EarthSky Community Photos. | Steven Bellavia captured this image on September 3, 2026, from Virginia and wrote: “Saturn, with moons Dione, Tethys and Rhea (left-to-right), from 07:30 UTC, September 03, 2026. I may have finally captured the elusive “spokes” which are fuzzy patches on the rings. But it could also be artifacts of capture and processing.” Thank you, Steven!
Tip 1: You need a telescope to see Saturn’s rings
Don’t expect to see the rings in binoculars. You really do need a telescope. A bigger telescope will show you more than a smaller telescope.
Saturn and its rings in 2026. The days around east and west quadrature (when Saturn is located 90 degrees from the sun) are better than opposition for seeing the shadow of or on the rings, and eclipses of the satellites. Image via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.
Tip 2: Consider the tilt of Saturn’s rings
Notice the tilt of the rings. As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical. In 2017, the north side of the rings opened up most widely (27 degrees), as seen from Earth. That’s the most open this side of the rings has been since 1988.
In 2025, the rings appeared edge-on as seen from Earth in March. After that, we began to see the south side of Saturn’s rings, which will gradually increase to a maximum inclination of 27 degrees by May 2032. By the way, they were almost look edge-on again in late November 2025. And around the October 2026 opposition, the rings are titled -7.5 degrees with the southern side of the ring plane exposed.
The tilt of Saturn’s rings has a great impact on the planet’s overall brightness as seen from Earth. In years when Saturn’s rings are edge-on (2009 and 2025), Saturn does appear considerably dimmer. A computer program by Tom Ruen simulated these Saturn views. Image via Wikimedia Commons (GFDL).
Tip 3: Can you see the rings in 3D?
Ask yourself … do Saturn’s rings look three-dimensional? Again quoting Alan MacRobert at SkyandTelescope.org:
Saturn has a more three-dimensional appearance than any other object in the sky; at least that’s how it looks to me with a 6-inch ‘scope on a night of fine seeing.
Shadows cast by the ring on the planet in front and by the planet on the farther ring can make the image of Saturn pop.
Tip 4: How’s the seeing?
What was Alan talking about in that quote above when he mentioned seeing? Both amateur and professional astronomers talk about the night’s seeing, which affects how clearly and sharply you can see a telescopic image. Seeing isn’t a quality of the telescope; it’s a quality of the air above you. It’s the reason the stars twinkle more on some nights than others.
When the air is particularly turbulent, astronomers say there’s bad seeing. The images in the telescope shimmy and dance. When the air is particularly still, astronomers say there’s good seeing. Seeing can shift from moment to moment as parcels of air move above you. So, as you’re gazing at Saturn, stand as quietly as you can – for as long as you can – and just look. You’ll notice moments when the image suddenly comes into sharper focus.
Other tips to consider
Once you get comfortable viewing Saturn – assuming you’re able to view it again and again, with a telescope of your own – you’ll begin to notice details in the rings.
Today, thanks to spacecraft, we know that Saturn’s rings are incredibly detailed. But, as you stand at your telescope gazing upward, you might be thrilled to witness just one primary division in the rings, the Cassini Division between the A and B rings, named for its French discoverer Jean Cassini.
Seeing this dark division is a good test of the night’s seeing and your telescope’s optical quality, and also of your own eyes’ ability to simply look and notice what you see. By the way, if you’re looking at the rings – which means you’re viewing Saturn through a telescope – also look for one or more of Saturn’s many moons, most notably Titan.
The Opposition Surge
A phenomenon that occurs when Saturn is at opposition is that the rings brighten for a few days. You can only see this a few nights on either side of opposition, which this year occurs on October 4.
This is the Seeliger Effect, which Hugo von Seeliger first described more than 100 years ago. Normally the rings appear as bright as the globe of the planet. But as the planet lines up with the Earth and the sun, more sunlight suddenly gets reflected back to us from the rings than from the globe, and the rings take on an additional level of brightness.
The two mechanisms for this brightening are shadow hiding and a coherent reflection of sunlight off the rings’ particles. Shadow hiding occurs because the shadows are the shortest on the ring particles. The coherent reflection of light occurs because light going straight into the ice particles reflects off of the inner surfaces, then straight back to where it came from.
This brightness surge lasts only a few days; see a study showing this increase. The window for this opportunity is the days around October 4.
Have fun!
Alas, you won’t see Saturn looking like this through a telescope. This is a spacecraft view from Cassini in 2016, showing Saturn’s northern hemisphere. Image via NASA/ JPL-Caltech/ Space Science Institute.
Bottom line: If you want to see Saturn’s rings at their best in 2026, late September and early October is a great time to look. Grab a telescope and read the tips found here!
The famous Grand Prismatic Spring in Yellowstone National Park is a sign of the geothermal activity in this region. The Yellowstone supervolcano has had 3 massive eruptions in history. What if one of those happened today? Would it end humanity? Image via Lucy Whitt. Used with permission.
What if a worst-case scenario Yellowstone supervolcano eruption happened? It would be a civilization-scale disaster. But it would not necessarily wipe out humanity.
The eruption would devastate much of North America. Massive ashfall, pyroclastic flows and infrastructure failures would disrupt civilization in this region. Plus, volcanic aerosols would cool the global climate.
The effects could last for decades. Food shortages, disease, economic disruption and climate changes could cause enormous loss of life. Yet ecosystems and agriculture would gradually recover and humanity would persist.
Would a Yellowstone supervolcano eruption end humanity today?
Around 631,000 years ago — a geological blink of an eye — catastrophe unfolded in what is now northwestern Wyoming in the U.S. During what is thought to have been a series of immense volcanic eruptions, life within hundreds of kilometers of the blasts was shattered. Ash was dispersed across much of North America and the effects were felt worldwide. This was a super-eruption of the massive volcanic system located in what is now Yellowstone National Park.
No known human witnessed the cataclysm. As far as we know, early humans had not yet reached the continent. Across oceans, perhaps early humans did wonder at the hazier skies and unusually vivid sunsets. Volcanic particles circulating in the sky cooled their climate and likely affected their weather patterns and lives. Whether they noted these changes — or connected them to any distant event — is unknowable.
Today, humanity would certainly notice. We already know that a super-eruption on this scale would be a threat to civilization as we know it. So what exactly would we experience if Yellowstone erupted? We are experts in disasters and volcanoes. What follows is a thought experiment into what might happen in the worst-case scenario. We’ve based our hypothesis on research and by examining how countries have dealt with disasters in recent years.
T-2 months
Shortly after 6 a.m., an analyst at the University of Utah Seismograph Stations sees a series of sharp spikes interrupting the usually quiet wavy lines recorded by Yellowstone’s earthquake monitors. The measurements represent earthquakes detected beneath Yellowstone overnight. The scientist raises an eyebrow and takes a deep breath. These observations don’t fit with Yellowstone’s usual behavior.
People often imagine Yellowstone as a sleeping “supervolcano”. It may sleep, but its geological processes never do. An array of instruments monitors its activity, and any changes in it. A dense network of seismometers records earthquakes in the region. Around the clock, data feeds in from GPS stations, strainmeters (instruments which measure deformations and changes in the shape of the Earth’s crust) and sensors positioned within its active geyser areas. Satellite observations, gas sampling and field surveys add plenty more information.
Scientists look at the number of earthquakes along with their location, depth and size. Earthquake “swarms” warrant particular attention, especially when they appear to be migrating through the crust (Earth’s solid, outermost rocky shell) or becoming progressively shallower. Such patterns can indicate that magma or pressurized hydrothermal fluids (hot, mineral-rich water) is moving upwards.
Our scientist is relieved to discover that most of the unusual tremors are tiny, too weak to have been felt. But together, they form an unusually concentrated swarm. The analyst checks the signals against neighboring seismometers and, more out of curiosity than concern, contacts colleagues at several partner organizations comprising the Yellowstone Volcano Observatory (YVO) in order to follow YVO’s response plan.
They deduce that, overnight, instruments have recorded a tightening cluster of earthquakes beneath Yellowstone’s vast caldera, which is roughly 55–70 kilometers (34–43 miles) across. Yellowstone experiences thousands of earthquakes each year, and swarms are not unusual. But this one appears to be migrating ever so slightly upwards. Still, an earthquake swarm by itself doesn’t mean Yellowstone is preparing to erupt, nor does ground deformation, changing temperatures or gas emissions. Scientists are more concerned about several such changes happening together.
The team of scientists decides to wait and see what happens next.
T-1 month
Four weeks later, the swarm has continued to migrate upwards. New events are also appearing along a narrow zone beneath the caldera, notes the analyst, who has now lost their appetite for both food and caution and is writing reports designed to be alarming. GPS stations above the swarm have begun moving apart. Measurements of strain have increased and satellite radar reveals the cause: there’s a broad area of accelerating uplift of the ground.
The surface of a volcano inflates and deflates as the magma chamber below it changes in pressure. Measuring this motion can help tell scientists whether a volcano is building to an eruption. Image via USGS and Jessica Murray-Moraleda, CC BY-SA.
Together, the observations are consistent with magma forcing its way into the crust, as seen in places like Hawai’i prior to eruptions. Reassuringly for YVO staff, Yellowstone has produced similarly alarming combinations of signals before with no subsequent eruptions. Between 2013 and 2014, parts of the caldera began rising at rates of more than 15 centimeters (6 inches) a year and earthquake activity increased.
This culminated in a magnitude 4.8 earthquake, the largest recorded at Yellowstone since 1975. Shortly after, the uplift changed to subsidence (the ground moving downward) and scientists concluded that the episode was associated with hydrothermal fluid movements rather than magma.
The Biscuit basin explosion at Yellowstone was an example of an eruption caused by hydrothermal fluid rather than magma.
Mindful of the need to keep the public informed without causing unnecessary alarm, YVO responds cautiously. A duty scientist assumes responsibility for assessing the incoming data. Additional, temporary seismometers and GPS units are deployed to provide more precise data, and gas and water are sampled more frequently.
YVO begins closer coordination with the National Park Service and emergency management authorities. They review road closures, public communications and evacuation plans. Perhaps ominously, but to err on the side of caution, Yellowstone’s Volcano Alert Level is raised from “normal” to “advisory”, indicating that unrest is above its established background level.
These developments are worrisome enough that scientists start speculating about a major eruption’s impacts. The media take an interest, but the volcanologists have learned how damaging it can be when volcanic uncertainties morph into a full-blown dispute, played out in public.
Scientists privately discuss differences in interpretations, agreeing on regular updates for the public via media briefings and social media postings. As the volcano’s activity continues to ramp up, high-level decision-makers are alerted that this situation could become a major catastrophe. The probability of it happening within three months increases from 6-9% to 21-27%.
Due to the uncertainties, the politicians make no specific declaration. The US’s Federal Emergency Management Agency nevertheless starts drawing up plans for a large-scale evacuation. They express confidence in public while perhaps fearing in private that a worst-case scenario could make it hopeless to try to save everyone.
Over the following fortnight, the unrest escalates dramatically. Earthquakes become more frequent and shallower. Long-period seismicity (much gentler earthquakes, usually caused by fluid movement rather than faults shifting and known to occur at Yellowstone) and sustained volcanic tremors suggest magma and pressurized fluids are forcing open fractures in the ground.
The uplift accelerates and GPS stations move centimeters in days. Geyser activity becomes increasingly erratic. Even the Old Faithful geyser becomes less faithful: its usually regular eruptions become harder to predict. Meanwhile, gas measurements and changes in spring water chemistry indicate an increased input of carbon dioxide and sulfurous gases into Yellowstone’s hydrothermal system. Taken together with the shallow earthquakes and rapid uplift, the concern is that magma may be moving upwards.
T-2 weeks: ‘It’s gonna blow!’
These new observations lead to a press conference describing an 85-92% probability of a cataclysmic eruption within three weeks. At this point, the YVO raises Yellowstone warning to “watch”, and the USGS raises the Aviation Color Code to orange, with aircraft rerouted around the region.
An evacuation zone extending 100 kilometers (62 miles) beyond Yellowstone National Park is announced, affecting roughly 200,000 residents, as well as thousands of visitors in the region. The topic now dominates both traditional and social media. The attention likely spawns detractors as well as conspiracists. The former claim that nothing will happen. The latter spread the disinformation that YVO is being paid by foreign shadow billionaires to bring down the U.S. so that other countries can control the world’s economy.
Now that a super-eruption appears imminent with high confidence, world leaders swing into action. They must make a choice: help each other as a global village or repeat COVID-19 style global shuttering.
If they choose collaboration, then they start evacuations, moving people as far as needed, including across international borders. This would involve supporting them with adequate homes, water, food, electricity and community through schools, jobs, transport and safety. Achieving all this seems unlikely, since most of the world’s population has always lacked it. Nonetheless, the U.S. has the money, skills and goods to evacuate and resettle the huge numbers, if leaders cooperate and use everything available.
More likely, many countries could be reticent to accept “volcano refugees,” making excuses — perhaps legitimate ones — that they don’t have the money, resources or space to safely settle so many people so swiftly. They are further stretched by those who self-evacuate through having more than one passport, along with the wealth or the social network to start afresh.
Charities step in to help some people leave on chartered planes, as well as via long, excruciating journeys on overcrowded trains and buses. The most marginalized and poorest may have no option but to stay behind. Some might join the minorities who do not believe the eruption will happen, who think their well-stocked underground bunkers will protect them (an overly optimistic belief), or who would rather die at home than live in a foreign land with a devastated world.
T=0
In an instant, seismic instruments are overwhelmed by an intense burst of shallow earthquakes. Expanding clouds of steam rise from newly opened cracks. The YVO and USGS have no choice but to raise the warning level and Aviation Color Codes to red: a dangerous eruption is imminent.
The eruption does not begin with the entire caldera exploding at once. Instead, rising magma intrudes into Yellowstone’s shallow hydrothermal system, rapidly vaporizing immense volumes of water. At atmospheric pressure, water can expand in volume around 1,700 times when converted to steam. Trapped beneath the surface, this rapid expansion triggers violent so-called phreatomagmatic explosions that send superheated steam, mud and shattered blocks of rock kilometers into the air.
There are no human casualties yet, thanks to the wide exclusion zones on land and in the air. Wildlife, livestock and vegetation are not as fortunate. Within roughly 4–6 kilometers (2.4-3.7 miles) of the initial eruption sites, the landscape is battered by falling rock, ash and mud. Beyond the exclusion zone, people watch an impressive two-kilometer-high (1.2 miles) plume rise into the sky, but it rapidly grows larger, and any sense of relief is short-lived.
A few hours later, gas-rich magma, 650-800°C (1,200-1,470°F) in temperature — well above the melting points of lead and zinc — breaks through the fractured surface. As the confining pressure falls, dissolved gases separate into distinct components from the melt and expand violently. The magma fragments into pumice (porous rock) and ash while tearing away huge fragments of the surrounding rock from the walls of the erupting vent.
Expanding gases and intense heat drive this material upwards, creating a vast eruption column rising 30–50 kilometers (18–31 miles) into the atmosphere. That’s far above commercial passenger aircraft, which usually cruise at up to about 13 kilometers (8 miles). On this clear morning, its upper reaches are visible from Denver, some 800 kilometers (500 miles) away.
As the eruption continues and the volume of material expelled mounts, scientists realize it might be the opening stages of a VEI 8 super-eruption (magnitude 8 or greater). That’s the highest formal notch on a scale used to measure the size of explosive volcanic eruptions. It was 74,000 years ago that humanity last witnessed this scale of eruption with Toba in Indonesia.
The immense umbrella cloud that forms does not behave like a normal ash plume that simply drifts with the prevailing wind. Its momentum initially drives ash outwards in every direction. It spreads hundreds of kilometers before high-altitude winds take over and carry fine ash thousands of kilometers downwind within a day.
After a few hours of continuous eruption, parts of the column collapse, generating scorching pyroclastic density currents (extremely hot, fast-moving mixtures of gas, ash and rock fragments). These surge for tens of kilometers, splintering trees, igniting forests and burying the remnants beneath hot ash and pumice.
Anyone within this zone is pulverized by the blasts, crisped by the heat or asphyxiated by the ash. There may be up to 1,000 immediate human deaths, including people who refused to move. It is too dangerous to recover most bodies. And even if it were possible, many bodies no longer exist to be recovered.
Outside the main pyroclastic density current zone, casualties mount from vehicle crashes as drivers lose visibility or skid due to ash, from heart and breathing difficulties and from suicide. Vegetation fires spreading beyond the immediate burn zone add perhaps hundreds of fatalities from burning, smoke inhalation and vehicle crashes.
As the magma continues to escape, sections of the unsupported ground subside, opening new fractures and vents while feeding further eruptive columns and pyroclastic density currents. Hundreds of kilometers away — in Denver and along the Canadian border — heavy ashfall darkens the sky, obstructs roads and disrupts power, water supplies and communications. This ash devastates farmland across at least eight states.
Further immediate deaths could result from loss of power disrupting traffic and street lights; curtailing health services including surgery and obtaining prescriptions; and electrocution, fire and carbon monoxide poisoning from trying to set up and operate home electricity generators. Looting and increasing crime during disasters is typically rare, but it could happen in a more desperate worst-case scenario, adding to the casualty toll.
Over the coming days, the eruption continues in pulses as sections of the caldera collapse and new vents open. Successive column collapses generate pyroclastic density currents with the resulting deposits reaching several hundred meters in thickness, as they did in the last super-eruption.
Nearby infrastructure is shattered and entombed beneath the deposits. Airports close because ash interferes with aircraft and other transport networks falter. Communities across all states bordering Wyoming face darkness, breathing difficulties and roofs collapsing under accumulated ash. As the eruption eventually begins to weaken, sulfur dioxide high in the atmosphere forms sunlight-reflecting sulphate aerosols that spread around the northern hemisphere to influence the world’s climate for several years.
T+3 days
Three days into the eruption, much of North America is living in the shadow of Yellowstone. Each successive powerful eruptive pulse sends another column tens of kilometers upwards, from where it spreads into a new umbrella cloud.
Within Wyoming and neighboring states, conditions are catastrophic. Billings, Montana, the nearest large city, is disappearing beneath what will eventually exceed a meter of ash (one published model of a Yellowstone super-eruption predicts the city as receiving up to 1.8 meters [6 feet] of ash). Salt Lake City, Utah, and Boise, Idaho, receive tens of centimeters. For southern Canada, much of the US and northern Mexico, day becomes twilight and breathing outdoors without masks becomes increasingly difficult. People on other continents watch in trepidation under vivid, red-orange sunrises and sunsets.
Back in the U.S., electricity networks begin failing. Warnings had not been heeded that damp ash conducts electricity, short circuiting power lines and substations. Ash clogs machinery and generator intakes. Its weight damages cables and weaker structures.
Infrastructure damage at Hebgen Lake due to the 7.2 magnitude earthquake of 1959. Image via I.J. Witkind. USGS Photographic Library/ Wikipedia.
As electricity fails, so do water pumps, sewage treatment, heating systems, fuel stations and mobile phone and internet networks. People are scared and supermarket shelves empty nationwide as regional and national supply chains begin to break down.
T+2 weeks
Over the following weeks, the crisis becomes one of survival. Repeated ashfall blocks roads, overwhelms drainage systems and damages roofs. During rain, dry ash turns into a dense slurry that makes clearance work harder. Airports remain closed or severely disrupted across much of North America, while railways, freight depots and farms struggle to operate. Livestock and crops die where pasture and water supplies are buried or contaminated by ash.
Large areas close to Yellowstone remain evacuated, while across the U.S., shelter, fuel, food and clean water become increasingly scarce. Some countries airlift or airdrop humanitarian relief supplies. But they are also concerned about stockpiling for themselves. Losses to agriculture, transport and insurance — with many other businesses and services closed — could lead Canada, Mexico and most Caribbean and Central American countries to declare states of emergency. This is partly due to direct impacts on those countries and partly due to disruption across the U.S. and people fleeing from it.
T+4 months
Several months later, eruptions have weakened to intermittent explosions, but the threat of renewed activity remains. For millions, the disaster is far from over. Dry, windy days lift ash back into the air, while rain and snow turn it into a heavy deposit blocking drains and damaging infrastructure. Eye and throat irritation are widespread. People with asthma and other respiratory conditions face serious health risks under reduced and overworked health services.
Water treatment and power plants struggle with ash contamination, equipment failures, lack of spare parts and overwhelming demand, disrupting essential medical and industrial processes. Crops across the most heavily affected regions have been buried. The loss of American and Canadian grain, maize and soya exports drives global food prices upwards.
Flights gradually resume in less affected areas, but airports across North America repeatedly close whenever winds remobilize the ash. The unreliable airspace and transport networks — coupled with agricultural losses, business disruption and reconstruction costs — trigger banking and insurance crises, producing a global recession.
Meanwhile, the atmospheric effects become global. Most volcanic ash has fallen out, but sulfur dioxide injected into the stratosphere produces sulphate aerosols which reflect a significant proportion of the sun’s energy. Scientists call it a “volcanic cooling episode,” avoiding the term “a new ice age”. Modelling suggests it’s unlikely to cool the global average by more than about 1.5°C, although particular regions and seasons could experience much larger changes. Notably, central North America remains far cooler than before the eruption.
T+10 years
In the years following the eruption, the world moves into long-term recovery and rebuilding. People across the world adapt to a more agrarian lifestyle, learning to fill the land with root vegetables, grains and legumes. With far less leisure time and diminished income, recreational facilities are turned over to food production, notably small-scale greenhouses and vertical farming for producing varied fruits, vegetables, nuts and legumes.
Livestock decreases due to lack of land and feed, opening up more space for crops. People still eating meat typically either hunt big game or trap smaller birds and mammals. Insect farming tends to dominate the re-establishment of bird or mammal farms. People living near coasts, rivers and lakes ramp up fishing, depleting stocks rapidly until controls are enacted in some locations, along with increased farming for seaweed. Where rules are not agreed or enforced, starvation and migration are rampant.
Freshwater availability varies. The world’s climate has changed, providing ample rainfall in some places while drying out others. Large-scale water treatment technology remains known and used. But supply lines for chemicals and spare parts are unreliable. Many people develop local approaches and manage while others suffer contaminated water and disease, including cholera, dengue fever and malaria, just as billions did before the eruption.
Before the eruption, around 4.4 billion people from the world’s population of 8.3 billion lacked full, safe freshwater access. A decade after the eruption, it’s possible that 4.8 billion people lack such freshwater, while the world’s population may have declined to 7.9 billion due to spikes in elderly and infant mortality.
For the eruption’s survivors, disease and death are still rising. The eruption may well provide substantive, long-term evidence for the carcinogenic level of silica in the ash. A small but statistically significant increase in diagnoses of both silicosis (an irreversible lung disease) and lung cancer appears from exposure to ash, with similar results for cardiovascular disease in people breathing in ash particles.
Rates are likely higher than measured, because health systems across a continent were knocked out by the eruption and struggling to recover ten years later. The worst part is that the lack of health systems means that many who are diagnosed cannot be treated properly. Survivable diagnoses become lethal.
Inside the eruption zone, two decades follow of a grey landscape. It appears almost lifeless, with the ash transformed into raging mudflows called lahars in every storm. But vegetation, starting with grasslands and shifting to forests, creeps back into the swathes wiped out in the explosion and people follow. These new pioneers coax the landscape into fertile framing, helping to feed hungry populations.
A lahar travels down a river valley in Guatemala near the Santa María volcano, 1989. Image via Wikipedia/ USGS geologist Jeff Marso.
The dispersed ash eventually settles out of the atmosphere. That permits the sun’s rays to shine fully on the surface again, reviving agriculture and ecosystems. It also revives fears of human-caused climate change, despite the volcano-induced reduction in greenhouse gas emissions. Scientists work hard to determine whether the global climate has been knocked onto a new trajectory — which might be better or worse for human beings — or whether the heat stored in the atmosphere and oceans from humanity’s greenhouse gas burning will once again force a rapidly heating globe.
Additionally, scientists want to calculate deaths, injuries and loss to quality of life. Excess mortality analyses could suggest 0.7-1.3 billion premature deaths due to the eruption and its impacts. Perhaps double that number experienced temporary or permanent health effects but survived, although some will say that 100% of humanity was directly affected.
The good news, at least for our species, is that this unstoppable power of volcanism changed the planet, but did not end humanity … or come close to doing so.
T+1 million years
A creature descends to Earth from a sleek spacecraft, still humanoid but far removed from its ancestor species Homo sapiens sapiens. Tjjze (the pronoun used) has absorbed all the scant information available about ancient “Earth” and is curious to learn more.
The most notable material is the rise of its first technological civilization just over a million years ago. This was followed by the species abandoning the planet as it changed 140,000-160,000 years ago — becoming taller, sleeker, with longer limbs, and with larger hands, heads and brains — having already established itself around the galaxy. In the remaining lore, myths recur of episodes of runaway planetary temperature changes, hot and cold, as well as a series of volcanic blasts that changed the globe.
Tjjze observes that the vegetation is lush and the H2O is plentiful. It provides ample food and water for the bizarre animals and ecosystems. A rapid scan reveals much below the surface. In fact, a large roughly ellipse-shaped ridge made of rock appears prominently underneath the top layers. Yes, this particular region, about 24.3 cqurzots in radius, is definitely lower than the vast plains outside the depression. This seems to indicate an ancient volcanic eruption. And to leave a scar this big, it must have been gigantic.
Tjjze warps the equivalent of the face into the equivalent of a frown as more data are revealed. Indeed, this definitely looks like a caldera. And the age is coming in at around a million years (plus/minus).
Could it have erupted during the time of the technological civilization? Or were they lucky to have just missed it? It is impossible to really know.
Bottom line: Yellowstone has undergone three massive super-eruptions in the past. If the Yellowstone supervolcano erupted today, would humanity survive?
The famous Grand Prismatic Spring in Yellowstone National Park is a sign of the geothermal activity in this region. The Yellowstone supervolcano has had 3 massive eruptions in history. What if one of those happened today? Would it end humanity? Image via Lucy Whitt. Used with permission.
What if a worst-case scenario Yellowstone supervolcano eruption happened? It would be a civilization-scale disaster. But it would not necessarily wipe out humanity.
The eruption would devastate much of North America. Massive ashfall, pyroclastic flows and infrastructure failures would disrupt civilization in this region. Plus, volcanic aerosols would cool the global climate.
The effects could last for decades. Food shortages, disease, economic disruption and climate changes could cause enormous loss of life. Yet ecosystems and agriculture would gradually recover and humanity would persist.
Would a Yellowstone supervolcano eruption end humanity today?
Around 631,000 years ago — a geological blink of an eye — catastrophe unfolded in what is now northwestern Wyoming in the U.S. During what is thought to have been a series of immense volcanic eruptions, life within hundreds of kilometers of the blasts was shattered. Ash was dispersed across much of North America and the effects were felt worldwide. This was a super-eruption of the massive volcanic system located in what is now Yellowstone National Park.
No known human witnessed the cataclysm. As far as we know, early humans had not yet reached the continent. Across oceans, perhaps early humans did wonder at the hazier skies and unusually vivid sunsets. Volcanic particles circulating in the sky cooled their climate and likely affected their weather patterns and lives. Whether they noted these changes — or connected them to any distant event — is unknowable.
Today, humanity would certainly notice. We already know that a super-eruption on this scale would be a threat to civilization as we know it. So what exactly would we experience if Yellowstone erupted? We are experts in disasters and volcanoes. What follows is a thought experiment into what might happen in the worst-case scenario. We’ve based our hypothesis on research and by examining how countries have dealt with disasters in recent years.
T-2 months
Shortly after 6 a.m., an analyst at the University of Utah Seismograph Stations sees a series of sharp spikes interrupting the usually quiet wavy lines recorded by Yellowstone’s earthquake monitors. The measurements represent earthquakes detected beneath Yellowstone overnight. The scientist raises an eyebrow and takes a deep breath. These observations don’t fit with Yellowstone’s usual behavior.
People often imagine Yellowstone as a sleeping “supervolcano”. It may sleep, but its geological processes never do. An array of instruments monitors its activity, and any changes in it. A dense network of seismometers records earthquakes in the region. Around the clock, data feeds in from GPS stations, strainmeters (instruments which measure deformations and changes in the shape of the Earth’s crust) and sensors positioned within its active geyser areas. Satellite observations, gas sampling and field surveys add plenty more information.
Scientists look at the number of earthquakes along with their location, depth and size. Earthquake “swarms” warrant particular attention, especially when they appear to be migrating through the crust (Earth’s solid, outermost rocky shell) or becoming progressively shallower. Such patterns can indicate that magma or pressurized hydrothermal fluids (hot, mineral-rich water) is moving upwards.
Our scientist is relieved to discover that most of the unusual tremors are tiny, too weak to have been felt. But together, they form an unusually concentrated swarm. The analyst checks the signals against neighboring seismometers and, more out of curiosity than concern, contacts colleagues at several partner organizations comprising the Yellowstone Volcano Observatory (YVO) in order to follow YVO’s response plan.
They deduce that, overnight, instruments have recorded a tightening cluster of earthquakes beneath Yellowstone’s vast caldera, which is roughly 55–70 kilometers (34–43 miles) across. Yellowstone experiences thousands of earthquakes each year, and swarms are not unusual. But this one appears to be migrating ever so slightly upwards. Still, an earthquake swarm by itself doesn’t mean Yellowstone is preparing to erupt, nor does ground deformation, changing temperatures or gas emissions. Scientists are more concerned about several such changes happening together.
The team of scientists decides to wait and see what happens next.
T-1 month
Four weeks later, the swarm has continued to migrate upwards. New events are also appearing along a narrow zone beneath the caldera, notes the analyst, who has now lost their appetite for both food and caution and is writing reports designed to be alarming. GPS stations above the swarm have begun moving apart. Measurements of strain have increased and satellite radar reveals the cause: there’s a broad area of accelerating uplift of the ground.
The surface of a volcano inflates and deflates as the magma chamber below it changes in pressure. Measuring this motion can help tell scientists whether a volcano is building to an eruption. Image via USGS and Jessica Murray-Moraleda, CC BY-SA.
Together, the observations are consistent with magma forcing its way into the crust, as seen in places like Hawai’i prior to eruptions. Reassuringly for YVO staff, Yellowstone has produced similarly alarming combinations of signals before with no subsequent eruptions. Between 2013 and 2014, parts of the caldera began rising at rates of more than 15 centimeters (6 inches) a year and earthquake activity increased.
This culminated in a magnitude 4.8 earthquake, the largest recorded at Yellowstone since 1975. Shortly after, the uplift changed to subsidence (the ground moving downward) and scientists concluded that the episode was associated with hydrothermal fluid movements rather than magma.
The Biscuit basin explosion at Yellowstone was an example of an eruption caused by hydrothermal fluid rather than magma.
Mindful of the need to keep the public informed without causing unnecessary alarm, YVO responds cautiously. A duty scientist assumes responsibility for assessing the incoming data. Additional, temporary seismometers and GPS units are deployed to provide more precise data, and gas and water are sampled more frequently.
YVO begins closer coordination with the National Park Service and emergency management authorities. They review road closures, public communications and evacuation plans. Perhaps ominously, but to err on the side of caution, Yellowstone’s Volcano Alert Level is raised from “normal” to “advisory”, indicating that unrest is above its established background level.
These developments are worrisome enough that scientists start speculating about a major eruption’s impacts. The media take an interest, but the volcanologists have learned how damaging it can be when volcanic uncertainties morph into a full-blown dispute, played out in public.
Scientists privately discuss differences in interpretations, agreeing on regular updates for the public via media briefings and social media postings. As the volcano’s activity continues to ramp up, high-level decision-makers are alerted that this situation could become a major catastrophe. The probability of it happening within three months increases from 6-9% to 21-27%.
Due to the uncertainties, the politicians make no specific declaration. The US’s Federal Emergency Management Agency nevertheless starts drawing up plans for a large-scale evacuation. They express confidence in public while perhaps fearing in private that a worst-case scenario could make it hopeless to try to save everyone.
Over the following fortnight, the unrest escalates dramatically. Earthquakes become more frequent and shallower. Long-period seismicity (much gentler earthquakes, usually caused by fluid movement rather than faults shifting and known to occur at Yellowstone) and sustained volcanic tremors suggest magma and pressurized fluids are forcing open fractures in the ground.
The uplift accelerates and GPS stations move centimeters in days. Geyser activity becomes increasingly erratic. Even the Old Faithful geyser becomes less faithful: its usually regular eruptions become harder to predict. Meanwhile, gas measurements and changes in spring water chemistry indicate an increased input of carbon dioxide and sulfurous gases into Yellowstone’s hydrothermal system. Taken together with the shallow earthquakes and rapid uplift, the concern is that magma may be moving upwards.
T-2 weeks: ‘It’s gonna blow!’
These new observations lead to a press conference describing an 85-92% probability of a cataclysmic eruption within three weeks. At this point, the YVO raises Yellowstone warning to “watch”, and the USGS raises the Aviation Color Code to orange, with aircraft rerouted around the region.
An evacuation zone extending 100 kilometers (62 miles) beyond Yellowstone National Park is announced, affecting roughly 200,000 residents, as well as thousands of visitors in the region. The topic now dominates both traditional and social media. The attention likely spawns detractors as well as conspiracists. The former claim that nothing will happen. The latter spread the disinformation that YVO is being paid by foreign shadow billionaires to bring down the U.S. so that other countries can control the world’s economy.
Now that a super-eruption appears imminent with high confidence, world leaders swing into action. They must make a choice: help each other as a global village or repeat COVID-19 style global shuttering.
If they choose collaboration, then they start evacuations, moving people as far as needed, including across international borders. This would involve supporting them with adequate homes, water, food, electricity and community through schools, jobs, transport and safety. Achieving all this seems unlikely, since most of the world’s population has always lacked it. Nonetheless, the U.S. has the money, skills and goods to evacuate and resettle the huge numbers, if leaders cooperate and use everything available.
More likely, many countries could be reticent to accept “volcano refugees,” making excuses — perhaps legitimate ones — that they don’t have the money, resources or space to safely settle so many people so swiftly. They are further stretched by those who self-evacuate through having more than one passport, along with the wealth or the social network to start afresh.
Charities step in to help some people leave on chartered planes, as well as via long, excruciating journeys on overcrowded trains and buses. The most marginalized and poorest may have no option but to stay behind. Some might join the minorities who do not believe the eruption will happen, who think their well-stocked underground bunkers will protect them (an overly optimistic belief), or who would rather die at home than live in a foreign land with a devastated world.
T=0
In an instant, seismic instruments are overwhelmed by an intense burst of shallow earthquakes. Expanding clouds of steam rise from newly opened cracks. The YVO and USGS have no choice but to raise the warning level and Aviation Color Codes to red: a dangerous eruption is imminent.
The eruption does not begin with the entire caldera exploding at once. Instead, rising magma intrudes into Yellowstone’s shallow hydrothermal system, rapidly vaporizing immense volumes of water. At atmospheric pressure, water can expand in volume around 1,700 times when converted to steam. Trapped beneath the surface, this rapid expansion triggers violent so-called phreatomagmatic explosions that send superheated steam, mud and shattered blocks of rock kilometers into the air.
There are no human casualties yet, thanks to the wide exclusion zones on land and in the air. Wildlife, livestock and vegetation are not as fortunate. Within roughly 4–6 kilometers (2.4-3.7 miles) of the initial eruption sites, the landscape is battered by falling rock, ash and mud. Beyond the exclusion zone, people watch an impressive two-kilometer-high (1.2 miles) plume rise into the sky, but it rapidly grows larger, and any sense of relief is short-lived.
A few hours later, gas-rich magma, 650-800°C (1,200-1,470°F) in temperature — well above the melting points of lead and zinc — breaks through the fractured surface. As the confining pressure falls, dissolved gases separate into distinct components from the melt and expand violently. The magma fragments into pumice (porous rock) and ash while tearing away huge fragments of the surrounding rock from the walls of the erupting vent.
Expanding gases and intense heat drive this material upwards, creating a vast eruption column rising 30–50 kilometers (18–31 miles) into the atmosphere. That’s far above commercial passenger aircraft, which usually cruise at up to about 13 kilometers (8 miles). On this clear morning, its upper reaches are visible from Denver, some 800 kilometers (500 miles) away.
As the eruption continues and the volume of material expelled mounts, scientists realize it might be the opening stages of a VEI 8 super-eruption (magnitude 8 or greater). That’s the highest formal notch on a scale used to measure the size of explosive volcanic eruptions. It was 74,000 years ago that humanity last witnessed this scale of eruption with Toba in Indonesia.
The immense umbrella cloud that forms does not behave like a normal ash plume that simply drifts with the prevailing wind. Its momentum initially drives ash outwards in every direction. It spreads hundreds of kilometers before high-altitude winds take over and carry fine ash thousands of kilometers downwind within a day.
After a few hours of continuous eruption, parts of the column collapse, generating scorching pyroclastic density currents (extremely hot, fast-moving mixtures of gas, ash and rock fragments). These surge for tens of kilometers, splintering trees, igniting forests and burying the remnants beneath hot ash and pumice.
Anyone within this zone is pulverized by the blasts, crisped by the heat or asphyxiated by the ash. There may be up to 1,000 immediate human deaths, including people who refused to move. It is too dangerous to recover most bodies. And even if it were possible, many bodies no longer exist to be recovered.
Outside the main pyroclastic density current zone, casualties mount from vehicle crashes as drivers lose visibility or skid due to ash, from heart and breathing difficulties and from suicide. Vegetation fires spreading beyond the immediate burn zone add perhaps hundreds of fatalities from burning, smoke inhalation and vehicle crashes.
As the magma continues to escape, sections of the unsupported ground subside, opening new fractures and vents while feeding further eruptive columns and pyroclastic density currents. Hundreds of kilometers away — in Denver and along the Canadian border — heavy ashfall darkens the sky, obstructs roads and disrupts power, water supplies and communications. This ash devastates farmland across at least eight states.
Further immediate deaths could result from loss of power disrupting traffic and street lights; curtailing health services including surgery and obtaining prescriptions; and electrocution, fire and carbon monoxide poisoning from trying to set up and operate home electricity generators. Looting and increasing crime during disasters is typically rare, but it could happen in a more desperate worst-case scenario, adding to the casualty toll.
Over the coming days, the eruption continues in pulses as sections of the caldera collapse and new vents open. Successive column collapses generate pyroclastic density currents with the resulting deposits reaching several hundred meters in thickness, as they did in the last super-eruption.
Nearby infrastructure is shattered and entombed beneath the deposits. Airports close because ash interferes with aircraft and other transport networks falter. Communities across all states bordering Wyoming face darkness, breathing difficulties and roofs collapsing under accumulated ash. As the eruption eventually begins to weaken, sulfur dioxide high in the atmosphere forms sunlight-reflecting sulphate aerosols that spread around the northern hemisphere to influence the world’s climate for several years.
T+3 days
Three days into the eruption, much of North America is living in the shadow of Yellowstone. Each successive powerful eruptive pulse sends another column tens of kilometers upwards, from where it spreads into a new umbrella cloud.
Within Wyoming and neighboring states, conditions are catastrophic. Billings, Montana, the nearest large city, is disappearing beneath what will eventually exceed a meter of ash (one published model of a Yellowstone super-eruption predicts the city as receiving up to 1.8 meters [6 feet] of ash). Salt Lake City, Utah, and Boise, Idaho, receive tens of centimeters. For southern Canada, much of the US and northern Mexico, day becomes twilight and breathing outdoors without masks becomes increasingly difficult. People on other continents watch in trepidation under vivid, red-orange sunrises and sunsets.
Back in the U.S., electricity networks begin failing. Warnings had not been heeded that damp ash conducts electricity, short circuiting power lines and substations. Ash clogs machinery and generator intakes. Its weight damages cables and weaker structures.
Infrastructure damage at Hebgen Lake due to the 7.2 magnitude earthquake of 1959. Image via I.J. Witkind. USGS Photographic Library/ Wikipedia.
As electricity fails, so do water pumps, sewage treatment, heating systems, fuel stations and mobile phone and internet networks. People are scared and supermarket shelves empty nationwide as regional and national supply chains begin to break down.
T+2 weeks
Over the following weeks, the crisis becomes one of survival. Repeated ashfall blocks roads, overwhelms drainage systems and damages roofs. During rain, dry ash turns into a dense slurry that makes clearance work harder. Airports remain closed or severely disrupted across much of North America, while railways, freight depots and farms struggle to operate. Livestock and crops die where pasture and water supplies are buried or contaminated by ash.
Large areas close to Yellowstone remain evacuated, while across the U.S., shelter, fuel, food and clean water become increasingly scarce. Some countries airlift or airdrop humanitarian relief supplies. But they are also concerned about stockpiling for themselves. Losses to agriculture, transport and insurance — with many other businesses and services closed — could lead Canada, Mexico and most Caribbean and Central American countries to declare states of emergency. This is partly due to direct impacts on those countries and partly due to disruption across the U.S. and people fleeing from it.
T+4 months
Several months later, eruptions have weakened to intermittent explosions, but the threat of renewed activity remains. For millions, the disaster is far from over. Dry, windy days lift ash back into the air, while rain and snow turn it into a heavy deposit blocking drains and damaging infrastructure. Eye and throat irritation are widespread. People with asthma and other respiratory conditions face serious health risks under reduced and overworked health services.
Water treatment and power plants struggle with ash contamination, equipment failures, lack of spare parts and overwhelming demand, disrupting essential medical and industrial processes. Crops across the most heavily affected regions have been buried. The loss of American and Canadian grain, maize and soya exports drives global food prices upwards.
Flights gradually resume in less affected areas, but airports across North America repeatedly close whenever winds remobilize the ash. The unreliable airspace and transport networks — coupled with agricultural losses, business disruption and reconstruction costs — trigger banking and insurance crises, producing a global recession.
Meanwhile, the atmospheric effects become global. Most volcanic ash has fallen out, but sulfur dioxide injected into the stratosphere produces sulphate aerosols which reflect a significant proportion of the sun’s energy. Scientists call it a “volcanic cooling episode,” avoiding the term “a new ice age”. Modelling suggests it’s unlikely to cool the global average by more than about 1.5°C, although particular regions and seasons could experience much larger changes. Notably, central North America remains far cooler than before the eruption.
T+10 years
In the years following the eruption, the world moves into long-term recovery and rebuilding. People across the world adapt to a more agrarian lifestyle, learning to fill the land with root vegetables, grains and legumes. With far less leisure time and diminished income, recreational facilities are turned over to food production, notably small-scale greenhouses and vertical farming for producing varied fruits, vegetables, nuts and legumes.
Livestock decreases due to lack of land and feed, opening up more space for crops. People still eating meat typically either hunt big game or trap smaller birds and mammals. Insect farming tends to dominate the re-establishment of bird or mammal farms. People living near coasts, rivers and lakes ramp up fishing, depleting stocks rapidly until controls are enacted in some locations, along with increased farming for seaweed. Where rules are not agreed or enforced, starvation and migration are rampant.
Freshwater availability varies. The world’s climate has changed, providing ample rainfall in some places while drying out others. Large-scale water treatment technology remains known and used. But supply lines for chemicals and spare parts are unreliable. Many people develop local approaches and manage while others suffer contaminated water and disease, including cholera, dengue fever and malaria, just as billions did before the eruption.
Before the eruption, around 4.4 billion people from the world’s population of 8.3 billion lacked full, safe freshwater access. A decade after the eruption, it’s possible that 4.8 billion people lack such freshwater, while the world’s population may have declined to 7.9 billion due to spikes in elderly and infant mortality.
For the eruption’s survivors, disease and death are still rising. The eruption may well provide substantive, long-term evidence for the carcinogenic level of silica in the ash. A small but statistically significant increase in diagnoses of both silicosis (an irreversible lung disease) and lung cancer appears from exposure to ash, with similar results for cardiovascular disease in people breathing in ash particles.
Rates are likely higher than measured, because health systems across a continent were knocked out by the eruption and struggling to recover ten years later. The worst part is that the lack of health systems means that many who are diagnosed cannot be treated properly. Survivable diagnoses become lethal.
Inside the eruption zone, two decades follow of a grey landscape. It appears almost lifeless, with the ash transformed into raging mudflows called lahars in every storm. But vegetation, starting with grasslands and shifting to forests, creeps back into the swathes wiped out in the explosion and people follow. These new pioneers coax the landscape into fertile framing, helping to feed hungry populations.
A lahar travels down a river valley in Guatemala near the Santa María volcano, 1989. Image via Wikipedia/ USGS geologist Jeff Marso.
The dispersed ash eventually settles out of the atmosphere. That permits the sun’s rays to shine fully on the surface again, reviving agriculture and ecosystems. It also revives fears of human-caused climate change, despite the volcano-induced reduction in greenhouse gas emissions. Scientists work hard to determine whether the global climate has been knocked onto a new trajectory — which might be better or worse for human beings — or whether the heat stored in the atmosphere and oceans from humanity’s greenhouse gas burning will once again force a rapidly heating globe.
Additionally, scientists want to calculate deaths, injuries and loss to quality of life. Excess mortality analyses could suggest 0.7-1.3 billion premature deaths due to the eruption and its impacts. Perhaps double that number experienced temporary or permanent health effects but survived, although some will say that 100% of humanity was directly affected.
The good news, at least for our species, is that this unstoppable power of volcanism changed the planet, but did not end humanity … or come close to doing so.
T+1 million years
A creature descends to Earth from a sleek spacecraft, still humanoid but far removed from its ancestor species Homo sapiens sapiens. Tjjze (the pronoun used) has absorbed all the scant information available about ancient “Earth” and is curious to learn more.
The most notable material is the rise of its first technological civilization just over a million years ago. This was followed by the species abandoning the planet as it changed 140,000-160,000 years ago — becoming taller, sleeker, with longer limbs, and with larger hands, heads and brains — having already established itself around the galaxy. In the remaining lore, myths recur of episodes of runaway planetary temperature changes, hot and cold, as well as a series of volcanic blasts that changed the globe.
Tjjze observes that the vegetation is lush and the H2O is plentiful. It provides ample food and water for the bizarre animals and ecosystems. A rapid scan reveals much below the surface. In fact, a large roughly ellipse-shaped ridge made of rock appears prominently underneath the top layers. Yes, this particular region, about 24.3 cqurzots in radius, is definitely lower than the vast plains outside the depression. This seems to indicate an ancient volcanic eruption. And to leave a scar this big, it must have been gigantic.
Tjjze warps the equivalent of the face into the equivalent of a frown as more data are revealed. Indeed, this definitely looks like a caldera. And the age is coming in at around a million years (plus/minus).
Could it have erupted during the time of the technological civilization? Or were they lucky to have just missed it? It is impossible to really know.
Bottom line: Yellowstone has undergone three massive super-eruptions in the past. If the Yellowstone supervolcano erupted today, would humanity survive?
