View at EarthSky Community Photos. | Filippo Galati in Sampieri, Sicily, Italy, shared this image. Filippo wrote: “On May 16, 2022, before the start of the lunar eclipse, I photographed a particularly favorable passage of the International Space Station over the skies of Sicily. It is framed by the ancient furnace Penna and highlighted in the sky by the constellation Ursa Major.” Thank you, Filippo!
A bird? A plane? It’s the International Space Station!
The International Space Station (ISS) has been orbiting our planet since 1998. From most locations on Earth – assuming you have clear night skies – you can see the ISS for yourself. It looks like a bright star, moving quickly from horizon to horizon.
But how do you know when to see the ISS pass overhead from your location?
NASA has a great tool to help. Sign up to the Spot the Station program and you’ll receive alerts to let you know when the ISS will be visible from your location, wherever you are in the world. Plus, there’s a map-based feature to track when to look for the station as it flies over you.
Typically, alerts are sent out a few times each month when the station’s orbit is near your location. You’ll get notices only when the ISS will be clearly visible from your location for at least a couple of minutes.
One note: those who live north of 51.6 degrees north latitude (for example, in Alaska) may want to visit the Spot the Station website directly to see upcoming sighting opportunities. This is because notifications in this region will be fairly rare.
How to spot the International Space Station
Spot the Station will tell you which direction to look for the ISS in your night sky. If you’re not sure about your directions, just note where the sun sets. You know it sets generally westward. So from there, you can easily find the direction where the station will appear (for example, in the southwest or northwest).
Via NASA’s service, the height at which the station will appear in your sky is given in degrees. And remember, 90 degrees is directly over your head. So any number less than 90 degrees will mean the station will appear somewhere between the horizon and the overhead mark.
Want a way to measure degrees on the sky’s dome? Make a fist, and stretch out your arm: your fist at arm’s length is equal to about 10 degrees. Then, just use the appropriate number of fist-lengths to find the location marker. For example, four fist-lengths from the horizon would be about 40 degrees.
And don’t worry, the station is bright! It’s hard to miss if you’re looking in the correct direction.
View at EarthSky Community Photos. | Mohammad Adeel in Lahore, Punjab, Pakistan, captured this image on June 2, 2023. Mohammad wrote: “It had been a while since ISS showed up in the sky, and tonight I had the chance to capture it with some interesting conjunctions. Planet Venus being at greatest western elongation and shining brightly was lining up with the twins (Pollux and Castor) in a straight line, while planet Mars was almost over the Beehive Cluster. And having ISS in the frame was too much of a busy sky not to be captured.” Thank you, Mohammad!
Two decades of human occupation
The first module of the ISS was launched into space in 1998. The initial construction of the station took about two years to complete. Human occupation of the station began on November 2, 2000. And since that time, the ISS has been continuously occupied.
The ISS serves as both an orbiting laboratory and a port for international spacecraft. It orbits at approximately 220 miles (350 km) above the Earth, and travels at an average speed of 17,227 miles per hour (27,724 km/h). It makes approximately 16 orbits around Earth every day.
The primary partnering countries involved in operating the ISS include the United States, Canada, Japan, several European countries and Russia. China has its own space station, Tiangong, with the first module launched in 2021 and the last of its three initial modules launched in November 2022.
Retirement of the International Space Station
The ISS can’t continue forever, and plans are already in place for its retirement. The station will be de-orbited and crashed into the Pacific as early as 2031. So use this guide and make the most of the ISS while it’s still in our skies!
View at EarthSky Community Photos. | Patricio Leon in Santiago, Chile, captured this shot of SpaceX’s Dragon capsule approaching the International Space Station on April 9, 2022. He wrote: “Imaged at dawn today, the chasing Dragon capsule appeared as a bright star close to the ISS at the telescope finder, a very nice surprise indeed. Actual docking took place 2 hours after. The station’s solar panels lie along our line of view so are poorly represented, and the bright sphere on the left of the main body is another docked Dragon capsule.” Thank you, Patricio!
Bottom line: Learn how to spot the International Space Station from your location.
View at EarthSky Community Photos. | Filippo Galati in Sampieri, Sicily, Italy, shared this image. Filippo wrote: “On May 16, 2022, before the start of the lunar eclipse, I photographed a particularly favorable passage of the International Space Station over the skies of Sicily. It is framed by the ancient furnace Penna and highlighted in the sky by the constellation Ursa Major.” Thank you, Filippo!
A bird? A plane? It’s the International Space Station!
The International Space Station (ISS) has been orbiting our planet since 1998. From most locations on Earth – assuming you have clear night skies – you can see the ISS for yourself. It looks like a bright star, moving quickly from horizon to horizon.
But how do you know when to see the ISS pass overhead from your location?
NASA has a great tool to help. Sign up to the Spot the Station program and you’ll receive alerts to let you know when the ISS will be visible from your location, wherever you are in the world. Plus, there’s a map-based feature to track when to look for the station as it flies over you.
Typically, alerts are sent out a few times each month when the station’s orbit is near your location. You’ll get notices only when the ISS will be clearly visible from your location for at least a couple of minutes.
One note: those who live north of 51.6 degrees north latitude (for example, in Alaska) may want to visit the Spot the Station website directly to see upcoming sighting opportunities. This is because notifications in this region will be fairly rare.
How to spot the International Space Station
Spot the Station will tell you which direction to look for the ISS in your night sky. If you’re not sure about your directions, just note where the sun sets. You know it sets generally westward. So from there, you can easily find the direction where the station will appear (for example, in the southwest or northwest).
Via NASA’s service, the height at which the station will appear in your sky is given in degrees. And remember, 90 degrees is directly over your head. So any number less than 90 degrees will mean the station will appear somewhere between the horizon and the overhead mark.
Want a way to measure degrees on the sky’s dome? Make a fist, and stretch out your arm: your fist at arm’s length is equal to about 10 degrees. Then, just use the appropriate number of fist-lengths to find the location marker. For example, four fist-lengths from the horizon would be about 40 degrees.
And don’t worry, the station is bright! It’s hard to miss if you’re looking in the correct direction.
View at EarthSky Community Photos. | Mohammad Adeel in Lahore, Punjab, Pakistan, captured this image on June 2, 2023. Mohammad wrote: “It had been a while since ISS showed up in the sky, and tonight I had the chance to capture it with some interesting conjunctions. Planet Venus being at greatest western elongation and shining brightly was lining up with the twins (Pollux and Castor) in a straight line, while planet Mars was almost over the Beehive Cluster. And having ISS in the frame was too much of a busy sky not to be captured.” Thank you, Mohammad!
Two decades of human occupation
The first module of the ISS was launched into space in 1998. The initial construction of the station took about two years to complete. Human occupation of the station began on November 2, 2000. And since that time, the ISS has been continuously occupied.
The ISS serves as both an orbiting laboratory and a port for international spacecraft. It orbits at approximately 220 miles (350 km) above the Earth, and travels at an average speed of 17,227 miles per hour (27,724 km/h). It makes approximately 16 orbits around Earth every day.
The primary partnering countries involved in operating the ISS include the United States, Canada, Japan, several European countries and Russia. China has its own space station, Tiangong, with the first module launched in 2021 and the last of its three initial modules launched in November 2022.
Retirement of the International Space Station
The ISS can’t continue forever, and plans are already in place for its retirement. The station will be de-orbited and crashed into the Pacific as early as 2031. So use this guide and make the most of the ISS while it’s still in our skies!
View at EarthSky Community Photos. | Patricio Leon in Santiago, Chile, captured this shot of SpaceX’s Dragon capsule approaching the International Space Station on April 9, 2022. He wrote: “Imaged at dawn today, the chasing Dragon capsule appeared as a bright star close to the ISS at the telescope finder, a very nice surprise indeed. Actual docking took place 2 hours after. The station’s solar panels lie along our line of view so are poorly represented, and the bright sphere on the left of the main body is another docked Dragon capsule.” Thank you, Patricio!
Bottom line: Learn how to spot the International Space Station from your location.
A mystery: How did the ancient builders of Egypt transport the heavy stones found today in Egyptian pyramids?
New research suggests a now-dry river played a role in the building of the pyramids. Scientists call this river the Ahramat. It was once a branch of the Nile. A major drought, some 4,200 years ago, might have led to its disappearance.
Satellite imagery, geophysical surveys and sediment cores confirm the existence of the Ahramat branch and its usage by ancient Egyptians, with many pyramids having causeways ending at the riverbanks of the Ahramat.
Egyptian pyramids: New finding
The amazing pyramids of Egypt … What a treasure to behold! But have you ever wondered why some of them – including the famous Giza pyramid complex – were built in the middle of nowhere, in a desert? And, how could Egyptians transport the tons-heavy blocks there? They were definitely smart and incredible builders. Still, there must be an explanation.
Now, according to a new paper from the peer-reviewed journal Nature – published on May 16, 2024 – the answer is simple. A chain of pyramids was built where, once, there was a river. We now call that ancient river the Ahramat, and it was a branch of the famous and very necessary Nile River.
It’s well known that civilizations settle where there are sources that will let people thrive. And to be sure, one of our most valuable sources is water. So, why would this advanced civilization build the famous pyramids in a desert? The answer, in fact, could well be this branch of the Nile, which has now disappeared.
There are thousands of pyramids in the world. Notably, around 100 are located in Egypt. And 31 of the Egyptian pyramids – including the Giza pyramid complex – were built along this 40-miles-long (64-km-long) stretch, called the Ahramat. These pyramids are concentrated in what is now a narrow, inhospitable desert. But when the ancient Egyptians built them over a nearly 1,000-year period, starting approximately 4,700 years ago, that area of the Western Desert – part of the Sahara – wasn’t entirely dry, scientists say.
Formerly, the Nile River used to have several branches. And the Ahramat branch was also close to the ancient Egyptian city of Memphis. This means that the pyramids were concentrated near the city and the river. Indeed, the pyramids would have been easily accessible via the river branch at the time they were built.
In addition, the authors of the paper found that many of the pyramids had causeways, which ended at the riverbanks of the Ahramat branch. This is evidence that the ancient Egyptians used the river for transporting construction materials, among other things.
How do researchers know?
Also, sedimentary evidence suggests that the Nile used to have a much higher discharge, with the river splitting into several branches.
With this in mind, the authors of the paper used satellite imagery to look for a former river branch running along the foothills of the Western Desert Plateau, very near to the pyramid fields.
In addition, they also used geophysical surveys and sediment cores to confirm the presence of river sediments and former channels beneath the modern land surface.
What happened to the river?
Over time, this branch of the Nile River became buried beneath farmland and desert. The authors suggest that an increased build-up of windblown sand, linked to a major drought which began approximately 4,200 years ago, could be one of the reasons for the Ahramat’s eventual silting up.
And, just like it happens to Venetians with their channels and gondolas, this now-dry river was an extremely useful source for Egyptians.
The results emphasize the significance of the Nile as a vital route and cultural lifeline for ancient Egyptians, while also shedding light on the historical impact of environmental changes on human society.
Moreover, further exploration to uncover additional extinct branches of the Nile could assist in prioritizing archaeological digs along its shores and safeguarding Egyptian cultural legacy.
Bottom line: Egyptian pyramids are marvelous constructions, a treasure to behold. How could the ancient Egyptians transport the tons-heavy blocks there? Now, a new explanation.
A mystery: How did the ancient builders of Egypt transport the heavy stones found today in Egyptian pyramids?
New research suggests a now-dry river played a role in the building of the pyramids. Scientists call this river the Ahramat. It was once a branch of the Nile. A major drought, some 4,200 years ago, might have led to its disappearance.
Satellite imagery, geophysical surveys and sediment cores confirm the existence of the Ahramat branch and its usage by ancient Egyptians, with many pyramids having causeways ending at the riverbanks of the Ahramat.
Egyptian pyramids: New finding
The amazing pyramids of Egypt … What a treasure to behold! But have you ever wondered why some of them – including the famous Giza pyramid complex – were built in the middle of nowhere, in a desert? And, how could Egyptians transport the tons-heavy blocks there? They were definitely smart and incredible builders. Still, there must be an explanation.
Now, according to a new paper from the peer-reviewed journal Nature – published on May 16, 2024 – the answer is simple. A chain of pyramids was built where, once, there was a river. We now call that ancient river the Ahramat, and it was a branch of the famous and very necessary Nile River.
It’s well known that civilizations settle where there are sources that will let people thrive. And to be sure, one of our most valuable sources is water. So, why would this advanced civilization build the famous pyramids in a desert? The answer, in fact, could well be this branch of the Nile, which has now disappeared.
There are thousands of pyramids in the world. Notably, around 100 are located in Egypt. And 31 of the Egyptian pyramids – including the Giza pyramid complex – were built along this 40-miles-long (64-km-long) stretch, called the Ahramat. These pyramids are concentrated in what is now a narrow, inhospitable desert. But when the ancient Egyptians built them over a nearly 1,000-year period, starting approximately 4,700 years ago, that area of the Western Desert – part of the Sahara – wasn’t entirely dry, scientists say.
Formerly, the Nile River used to have several branches. And the Ahramat branch was also close to the ancient Egyptian city of Memphis. This means that the pyramids were concentrated near the city and the river. Indeed, the pyramids would have been easily accessible via the river branch at the time they were built.
In addition, the authors of the paper found that many of the pyramids had causeways, which ended at the riverbanks of the Ahramat branch. This is evidence that the ancient Egyptians used the river for transporting construction materials, among other things.
How do researchers know?
Also, sedimentary evidence suggests that the Nile used to have a much higher discharge, with the river splitting into several branches.
With this in mind, the authors of the paper used satellite imagery to look for a former river branch running along the foothills of the Western Desert Plateau, very near to the pyramid fields.
In addition, they also used geophysical surveys and sediment cores to confirm the presence of river sediments and former channels beneath the modern land surface.
What happened to the river?
Over time, this branch of the Nile River became buried beneath farmland and desert. The authors suggest that an increased build-up of windblown sand, linked to a major drought which began approximately 4,200 years ago, could be one of the reasons for the Ahramat’s eventual silting up.
And, just like it happens to Venetians with their channels and gondolas, this now-dry river was an extremely useful source for Egyptians.
The results emphasize the significance of the Nile as a vital route and cultural lifeline for ancient Egyptians, while also shedding light on the historical impact of environmental changes on human society.
Moreover, further exploration to uncover additional extinct branches of the Nile could assist in prioritizing archaeological digs along its shores and safeguarding Egyptian cultural legacy.
Bottom line: Egyptian pyramids are marvelous constructions, a treasure to behold. How could the ancient Egyptians transport the tons-heavy blocks there? Now, a new explanation.
ESA’s Meteosat Third Generation Imager weather satellite, which usually spots lightning from space, saw the May 18, 2024, fireball for 6 seconds as it streaked across Portugal into the Atlantic Ocean. See videos of the Portugal fireball below. Image via ESA/ EUMETSAT.
Fireball spotted from above and below
On May 18, 2024, a brilliant fireball lit up the skies over Portugal and Spain. At 22:46 UTC, locals noticed the sky turn bright with a distinct bluish hue as the fireball coasted overhead. Experts with ESA said on Sunday it was most likely a comet fragment. Many people captured videos of the event and shared them on social media. And yesterday (May 22), ESA said a weather satellite meant to track lightning captured the signature of the fireball as it headed toward its end in the Atlantic Ocean.
In addition, a camera with ESA’s AllSky7 network also caught the fireball. This camera is part of the Planetary Defence Office. ESA said they estimated the object was about 3 feet (1 meter) in size and between 1,100 and 2,200 pounds (550 and 1,000 kg).
— Márcio Santos – Meteorologia e Ambiente (@MeteoTrasMontPT) May 18, 2024
Animals saw it, too
And to be sure, it wasn’t just people who witnessed the event. For example, watch these ducks in a farmyard in Portugal notice the bright flash above. Perhaps they were thinking: “Our ancestors warned us about this!”
Bottom line: The Portugal fireball that brightened skies on May 18, 2024, was captured from the ground on video and from satellites in space. The fireball was most likely a comet fragment.
ESA’s Meteosat Third Generation Imager weather satellite, which usually spots lightning from space, saw the May 18, 2024, fireball for 6 seconds as it streaked across Portugal into the Atlantic Ocean. See videos of the Portugal fireball below. Image via ESA/ EUMETSAT.
Fireball spotted from above and below
On May 18, 2024, a brilliant fireball lit up the skies over Portugal and Spain. At 22:46 UTC, locals noticed the sky turn bright with a distinct bluish hue as the fireball coasted overhead. Experts with ESA said on Sunday it was most likely a comet fragment. Many people captured videos of the event and shared them on social media. And yesterday (May 22), ESA said a weather satellite meant to track lightning captured the signature of the fireball as it headed toward its end in the Atlantic Ocean.
In addition, a camera with ESA’s AllSky7 network also caught the fireball. This camera is part of the Planetary Defence Office. ESA said they estimated the object was about 3 feet (1 meter) in size and between 1,100 and 2,200 pounds (550 and 1,000 kg).
— Márcio Santos – Meteorologia e Ambiente (@MeteoTrasMontPT) May 18, 2024
Animals saw it, too
And to be sure, it wasn’t just people who witnessed the event. For example, watch these ducks in a farmyard in Portugal notice the bright flash above. Perhaps they were thinking: “Our ancestors warned us about this!”
Bottom line: The Portugal fireball that brightened skies on May 18, 2024, was captured from the ground on video and from satellites in space. The fireball was most likely a comet fragment.
Is it a bird? No. It’s an artist’s concept of a dromaeosaur, nesting in snow. This species of warm-blooded dinosaurs lived during the Cretaceous Period, 145 to 66 million years ago. Image via Davide Bonadonna/ Universidade de Vigo/ UCL.
Warm-blooded dinosaurs were birds’ ancestors
Dinosaurs first came into prominence 230 million years ago. And almost all perished 66 million years ago, when an asteroid crashed to Earth. But, according to the fossil record, some dinosaurs at the time of that great extinction had traits seen in warm-blooded animals. They were able to control their body temperatures. They could thrive in colder climates. As the fossil record now shows, some of these warm-blooded dinosaurs had feathers to conserve body heat. On May 15, 2024, the University College London said warm-blooded dinosaurs arose about 180 million years ago. These are the dinosaurs that survived the asteroid crash and lived to produce descendants: our modern-day birds.
These warm-blooded dinosaurs arose during the Early Jurassic Epoch and were able to evolve in response to extreme changes in climate. That’s according to the study the researchers published in the journal Current Biology on May 15, 2024.
A sweeping look at dinosaurs
People once thought all dinosaurs were cold-blooded creatures, stereotyped as sluggish, lumbering beasts. The body temperature of cold-blooded animals, such as reptiles, is the same as the animal’s environment. So, they need warm environments to be active. That’s why cold-blooded animals of today are mostly found in warm climates, while those in temperate climates need to hibernate during the cold season.
The researchers analyzed what’s known about dinosaurs in the fossil record spanning 230 to 66 million years ago. How were different species distributed across the globe at different points in time? What were their evolutionary relationships? And what were their climate and geographic conditions?
What the study revealed
Some interesting observations emerged in their analysis. They learned that during the Early Jurassic Epoch, 201 to 175 million years ago, two kinds of dinosaurs adapted to cold climates. One of them was the theropods (meat-eating dinosaurs related to T. rex and Velociraptor). The other kind was ornithischians (relatives of plant-eaters like Stegosaurus and Triceratops). The adaptation of theropods and ornithischians to colder climates indicated that these dinosaurs could regulate their body temperature.
A Triceratops fossil at the Los Angeles Museum of Natural History. Triceratops lived during the Cretaceous Period, about 68 to 66 million years ago. But Early Jurassic climatic changes likely shaped its evolutionary path. Image via Allie Caulfield/ Wikimedia Commons.
Meanwhile, a third type of dinosaur, the sauropods (relatives of Brontosaurus and Diplodocus) remained in warmer climates, perhaps hinting of a cold-blooded body.
During the timeframe of these evolutionary changes, there was a period of widespread volcanic activity that caused adverse climatic changes, resulting in the extinction of many species. It’s known as the Jenkyns Event, and it took place around 183 million years ago.
This research suggests a close connection between climate and how dinosaurs evolved. It sheds new light on how birds might have inherited a unique biological trait from dinosaur ancestors and the different ways dinosaurs adapted to complex and long-term environmental changes.
Our analyses show that different climate preferences emerged among the main dinosaur groups around the time of the Jenkyns Event 183 million years ago, when intense volcanic activity led to global warming and extinction of plant groups.
At this time, many new dinosaur groups emerged. The adoption of endothermy [the ability to regulate body temperature], perhaps a result of this environmental crisis, may have enabled theropods and ornithischians to thrive in colder environments, allowing them to be highly active and sustain activity over longer periods, to develop and grow faster and produce more offspring.
Theropods also include birds, and our study suggests that birds’ unique temperature regulation may have had its origin in this Early Jurassic Epoch.
Sauropods, on the other hand, which stayed in warmer climates, grew to a gigantic size at around this time, another possible adaptation due to environmental pressure. Their smaller surface area to volume ratio would have meant these larger creatures would lose heat at a reduced rate, allowing them to stay active for longer.
Bottom line: According to a new study, warm-blooded dinosaurs emerged about 180 million years ago, evolving in response to adverse climatic changes.
Is it a bird? No. It’s an artist’s concept of a dromaeosaur, nesting in snow. This species of warm-blooded dinosaurs lived during the Cretaceous Period, 145 to 66 million years ago. Image via Davide Bonadonna/ Universidade de Vigo/ UCL.
Warm-blooded dinosaurs were birds’ ancestors
Dinosaurs first came into prominence 230 million years ago. And almost all perished 66 million years ago, when an asteroid crashed to Earth. But, according to the fossil record, some dinosaurs at the time of that great extinction had traits seen in warm-blooded animals. They were able to control their body temperatures. They could thrive in colder climates. As the fossil record now shows, some of these warm-blooded dinosaurs had feathers to conserve body heat. On May 15, 2024, the University College London said warm-blooded dinosaurs arose about 180 million years ago. These are the dinosaurs that survived the asteroid crash and lived to produce descendants: our modern-day birds.
These warm-blooded dinosaurs arose during the Early Jurassic Epoch and were able to evolve in response to extreme changes in climate. That’s according to the study the researchers published in the journal Current Biology on May 15, 2024.
A sweeping look at dinosaurs
People once thought all dinosaurs were cold-blooded creatures, stereotyped as sluggish, lumbering beasts. The body temperature of cold-blooded animals, such as reptiles, is the same as the animal’s environment. So, they need warm environments to be active. That’s why cold-blooded animals of today are mostly found in warm climates, while those in temperate climates need to hibernate during the cold season.
The researchers analyzed what’s known about dinosaurs in the fossil record spanning 230 to 66 million years ago. How were different species distributed across the globe at different points in time? What were their evolutionary relationships? And what were their climate and geographic conditions?
What the study revealed
Some interesting observations emerged in their analysis. They learned that during the Early Jurassic Epoch, 201 to 175 million years ago, two kinds of dinosaurs adapted to cold climates. One of them was the theropods (meat-eating dinosaurs related to T. rex and Velociraptor). The other kind was ornithischians (relatives of plant-eaters like Stegosaurus and Triceratops). The adaptation of theropods and ornithischians to colder climates indicated that these dinosaurs could regulate their body temperature.
A Triceratops fossil at the Los Angeles Museum of Natural History. Triceratops lived during the Cretaceous Period, about 68 to 66 million years ago. But Early Jurassic climatic changes likely shaped its evolutionary path. Image via Allie Caulfield/ Wikimedia Commons.
Meanwhile, a third type of dinosaur, the sauropods (relatives of Brontosaurus and Diplodocus) remained in warmer climates, perhaps hinting of a cold-blooded body.
During the timeframe of these evolutionary changes, there was a period of widespread volcanic activity that caused adverse climatic changes, resulting in the extinction of many species. It’s known as the Jenkyns Event, and it took place around 183 million years ago.
This research suggests a close connection between climate and how dinosaurs evolved. It sheds new light on how birds might have inherited a unique biological trait from dinosaur ancestors and the different ways dinosaurs adapted to complex and long-term environmental changes.
Our analyses show that different climate preferences emerged among the main dinosaur groups around the time of the Jenkyns Event 183 million years ago, when intense volcanic activity led to global warming and extinction of plant groups.
At this time, many new dinosaur groups emerged. The adoption of endothermy [the ability to regulate body temperature], perhaps a result of this environmental crisis, may have enabled theropods and ornithischians to thrive in colder environments, allowing them to be highly active and sustain activity over longer periods, to develop and grow faster and produce more offspring.
Theropods also include birds, and our study suggests that birds’ unique temperature regulation may have had its origin in this Early Jurassic Epoch.
Sauropods, on the other hand, which stayed in warmer climates, grew to a gigantic size at around this time, another possible adaptation due to environmental pressure. Their smaller surface area to volume ratio would have meant these larger creatures would lose heat at a reduced rate, allowing them to stay active for longer.
Bottom line: According to a new study, warm-blooded dinosaurs emerged about 180 million years ago, evolving in response to adverse climatic changes.
Two hours after sunset on May 22, the full Flower Moon glows brightly in the southeast above red Antares, the brightest star in Scorpius. The bright star Zubenelgenubi is also nearby. You can see the full moon cross the sky all night. Chart via EarthSky.
When and where to watch in 2024: Look for the bright, round moon rising low in the southeast after sunset on May 22. It reaches its highest point in the sky after midnight, and lies low in the southwest shortly before sunrise. Crest of the full moon falls at 13:53 UTC on May 23, 2024. That’s 8:53 a.m. CDT on May 23 in central North America. So, if you live in central North America, your fullest moon falls a few hours after sunrise on May 23 and after it has already set. The rising moon in the southeast on May 23 will also appear full.
At full moon, the sun, Earth, and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.
Moon looks full over 2 nights
At full moon, the sun, Earth, and moon align in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – faces us. That’s why the moon looks full. Note that the moon will look round for a day or two around full moon. Because the May full moon occurs in the morning on May 23, the moon will look full on the overnights of May 22 and 23.
On May 23, 2024, the bright red star Antares in Scorpius the Scorpion will lie close to the full moon. Full moon will occur at 13:53 UTC (8:53 a.m. CDT) on May 23, 2024. It’ll be visible all night. Also, sky watchers in the Americas, Western Africa and Middle Africa will see the moon pass in front of – or occult – Antares near 3 UTC on May 24. Other locations may see Antares very close to the limb of the moon. Chart via EarthSky.
It’s the Flower Moon
All the full moons have nicknames. Popular names for May’s full moon include the Planting Moon and the Milk Moon, but the Flower Moon is the most common. As you might expect, the name Flower Moon recognizes the blooming of wildflowers and garden flowers, many giving an enchanting appearance in the light of May’s full moon.
Arc of the May full moon
The moon’s arc across our sky varies from month to month and from season to season. Every full moon rises along the eastern horizon, opposite the sun as it sets in the west. Every full moon arcs across the sky throughout the night and sets along the western horizon around dawn.
For us in the Northern Hemisphere, the arc of May’s full moon is lower than the paths of the full moons since December, but higher than the next one which falls on June 21 in North America.
For Northern Hemisphere viewers, the arc across the sky of the May full moon is a bit higher than for the June full moon, the lowest of the year. And it is much lower than the highest of the year, the arc of the December full moon. Chart via EarthSky.
For those folks in the Southern Hemisphere, the full moon’s arc across the sky is climbing higher with each successive month since December, and will continue to do so until the full moon nearest the June solstice.
For Southern Hemisphere viewers, the arc across the sky of the May full moon is a bit lower than for the June full moon, the highest of the year. And it is much higher than the lowest of the year, that of the December full moon. Chart via EarthSky.
The May full moon is in Libra
As seen from the Americas, the full moon on the evening of May 22 is located in the direction of the constellation Libra the Scales. Just before sunrise on May 23, when the moon nears it fullest, it lies near Libra’s eastern border with Scorpius. On the night of May 23, when it still looks full, it glows next to Scorpius’ brightest star, Antares.
The May 2024 full moon occurs on the overnight of May 22 and lies in the eastern half of the constellation Libra. Chart via EarthSky.
Bottom line: The May full moon occurs in the morning of May 23, but looks full on the previous evening and as it rises on May 23.
Two hours after sunset on May 22, the full Flower Moon glows brightly in the southeast above red Antares, the brightest star in Scorpius. The bright star Zubenelgenubi is also nearby. You can see the full moon cross the sky all night. Chart via EarthSky.
When and where to watch in 2024: Look for the bright, round moon rising low in the southeast after sunset on May 22. It reaches its highest point in the sky after midnight, and lies low in the southwest shortly before sunrise. Crest of the full moon falls at 13:53 UTC on May 23, 2024. That’s 8:53 a.m. CDT on May 23 in central North America. So, if you live in central North America, your fullest moon falls a few hours after sunrise on May 23 and after it has already set. The rising moon in the southeast on May 23 will also appear full.
At full moon, the sun, Earth, and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.
Moon looks full over 2 nights
At full moon, the sun, Earth, and moon align in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – faces us. That’s why the moon looks full. Note that the moon will look round for a day or two around full moon. Because the May full moon occurs in the morning on May 23, the moon will look full on the overnights of May 22 and 23.
On May 23, 2024, the bright red star Antares in Scorpius the Scorpion will lie close to the full moon. Full moon will occur at 13:53 UTC (8:53 a.m. CDT) on May 23, 2024. It’ll be visible all night. Also, sky watchers in the Americas, Western Africa and Middle Africa will see the moon pass in front of – or occult – Antares near 3 UTC on May 24. Other locations may see Antares very close to the limb of the moon. Chart via EarthSky.
It’s the Flower Moon
All the full moons have nicknames. Popular names for May’s full moon include the Planting Moon and the Milk Moon, but the Flower Moon is the most common. As you might expect, the name Flower Moon recognizes the blooming of wildflowers and garden flowers, many giving an enchanting appearance in the light of May’s full moon.
Arc of the May full moon
The moon’s arc across our sky varies from month to month and from season to season. Every full moon rises along the eastern horizon, opposite the sun as it sets in the west. Every full moon arcs across the sky throughout the night and sets along the western horizon around dawn.
For us in the Northern Hemisphere, the arc of May’s full moon is lower than the paths of the full moons since December, but higher than the next one which falls on June 21 in North America.
For Northern Hemisphere viewers, the arc across the sky of the May full moon is a bit higher than for the June full moon, the lowest of the year. And it is much lower than the highest of the year, the arc of the December full moon. Chart via EarthSky.
For those folks in the Southern Hemisphere, the full moon’s arc across the sky is climbing higher with each successive month since December, and will continue to do so until the full moon nearest the June solstice.
For Southern Hemisphere viewers, the arc across the sky of the May full moon is a bit lower than for the June full moon, the highest of the year. And it is much higher than the lowest of the year, that of the December full moon. Chart via EarthSky.
The May full moon is in Libra
As seen from the Americas, the full moon on the evening of May 22 is located in the direction of the constellation Libra the Scales. Just before sunrise on May 23, when the moon nears it fullest, it lies near Libra’s eastern border with Scorpius. On the night of May 23, when it still looks full, it glows next to Scorpius’ brightest star, Antares.
The May 2024 full moon occurs on the overnight of May 22 and lies in the eastern half of the constellation Libra. Chart via EarthSky.
Bottom line: The May full moon occurs in the morning of May 23, but looks full on the previous evening and as it rises on May 23.
The constellation Virgo the Maiden is easy to find by using the handle of the Big Dipper to arc to Arcturus in Boötes, then speeding on (spiking down) to Spica, Virgo’s brightest star. Image via EarthSky.
The constellation Virgo the Maiden
From the Northern Hemisphere, Virgo the Maiden appears high above the southern horizon on May evenings. And this is the best time of year to view this constellation, which is the largest of the zodiac. As a matter of fact, Virgo is also the 2nd-largest constellation overall, after Hydra. Plus, thanks to its brightest star, Spica, there’s an easy trick to finding this constellation.
So, to find Virgo, remember this handy mnemonic device: Arc to Arcturus and speed on (spike) to Spica. What does that mean? Using the readily identifiable Big Dipper, you can follow the curve of its handle as you arc to a bright orangish star named Arcturus in the constellation Boötes. Then “drive a spike” (or sometimes the saying is “speed on down”) to Spica.
Spica is a blue-white, 1st-magnitude star near the center of Virgo.
First, follow the curve in the Big Dipper’s handle to the bright orange star Arcturus. Then extend that line to Spica. To be sure you’ve found Spica, look for a lopsided square pattern nearby: that’s Corvus the Crow. Image via Chelynne Campion.
The stars of the Maiden
Spica, which marks a bundle of wheat that the Maiden is holding, is the 15th brightest star in the sky. Spica is a magnitude 1.04 star that lies 250 light-years from Earth.
Then the next brightest star in Virgo is the binary star Gamma Virginis, or Porrima. Porrima is magnitude 2.74 and lies near the center of the constellation, above (northwest of) Spica. It lies 38 light-years away. Next, the 3rd brightest star is at the northern reaches of the constellation. Vindemiatrix is a magnitude 2.82 star located 109 light-years away.
Virgo the Maiden and its stars. Image via the International Astronomical Union (IAU).Here’s a classical illustration of the constellation Virgo the Maiden, via Urania’s Mirror/ Wikipedia (public domain).
The Virgo Cluster
Virgo is famous for its thousands of galaxies. One grouping – the Virgo Cluster – is near the border with Coma Berenices, west of Vindemiatrix. The Virgo Cluster is the nearest large group of galaxies to the Milky Way. The Virgo Cluster lies at the center of the Local Supercluster, a massive group containing clusters of galaxies. The Local Group of galaxies, which includes the Milky Way, is also part of the Local Supercluster.
Additionally, the gravitational pull from the Virgo Cluster in the Local Supercluster is slowing the escape velocity of the Milky Way and our Local Group. So the Virgo cluster is one of the few places in the universe we are speeding toward. Therefore, the galaxies in the Virgo Cluster are some of the few we see with a blueshift instead of a redshift. One day, these many galaxies will merge into one huge conglomeration.
In fact, the galaxy with one of the highest blueshifts lies right on the border of Virgo and Coma Berenices. This galaxy, M90, is moving rapidly among the other objects in the Virgo Cluster. That’s because it’s also being stripped of gas and dust due to its close quarters with the other galaxies. At magnitude 9.5, you can see this galaxy in a telescope across the 60 million light-year span.
In addition, other galaxies between 8th and 9th magnitude in this location are M49, M58, M59, M60, M84, M86, M87, and M89. Even more galaxies come into view if you scan along the line between Virgo and Coma Berenices.
M87 is a special galaxy that deserves to be singled out from the Virgo Cluster. It shines at magnitude 8.6 and is therefore easy to detect in any telescope and even in some binoculars. M87 lies about 60 million light-years away. Its potato-shaped clump of stars extends well over half a million light-years across. Additionally, it is thought to be five times the size of the Milky Way’s diameter. However, the diameter of the galaxy’s halo is about a million light-years, and while that is large, astronomers expected it to be even larger. They believe something cut the halo off early on in M87’s formation.
In fact, M87 is home to the largest known number of globular clusters. For comparison, the Milky Way has about 200 globulars, while M87 has thousands. These clusters may be dwarf galaxies that M87’s gravitation sucked in.
Another amazing feature of M87 is its jet that extends outward from the core for thousands of light-years. A monster black hole at the galaxy’s core is the source of the jet. In fact, M87’s black hole was the 1st ever imaged, in 2019. Then, recently that image was enhanced and released with more detail in April 2023. Plus, its black hole and its jet were imaged together for 1st time ever in April 2023.
View larger. | An optical light image of the jet erupting from the black hole at the core of galaxy Messier 87 (M87 or NGC 4486). The Hubble Space Telescope took this image on July 6, 2000. Image via NASA/ The Hubble Heritage Team (STScI/AURA)/ Wikimedia Commons (public doman).
The Sombrero Galaxy
Not to be overlooked is another bright and notable galaxy that’s apart from the large cluster: M104, or the Sombrero Galaxy. It’s located on the southeastern border of the constellation with Corvus the Crow. Without a doubt, M104 is a stunning galaxy in photographs. Even better, at magnitude 8.3, you can see it in small telescopes. It’s an edge-on, dusty spiral galaxy with a bright core. M104 lies approximately 55 million light-years away.
M104, or the Sombrero Galaxy, lies in the constellation Virgo the Maiden. Image via ESA/ Hubblesite/ Wikimedia Commons (public domain).
Virgo in mythology
The constellation Virgo is linked to the myth of Demeter, the harvest goddess, and her daughter Persephone. According to the myth, it once was always springtime on Earth. But then the god of the underworld, Hades, kidnapped Persephone.
Demeter, overcome with grief, abandoned her role as an Earth goddess. The world’s fruitfulness and fertility suffered. So Zeus insisted that Hades return Persephone to Demeter. But Zeus set a condition. He said Persephone must not eat until she returned to her home. That’s when Hades gave Persephone a pomegranate. It’s said that Persephone ate just six seeds.
So Persephone returned to her mother. But – because of the pomegranate – she has to return to the underworld for half of every year. To this day, spring returns to the Northern Hemisphere when Persephone reunites with Demeter. Then the winter season reigns when Persephone dwells in the underworld. Considering this, from the perspective of the Northern Hemisphere, Virgo is absent from early evening sky in late autumn, winter and early spring. Virgo’s return to the sky at nightfall – in the months of April and May – coincides with the season of spring.
The Return of Persephone” rel=”noopener” target=”_blank”>Persephone by Frederic Leighton. Image via Wikipedia (public domain).
Bottom line: Virgo the Maiden is the largest of the zodiac constellations. A handy mnemonic device – using the Big Dipper and its bright star Spica – make it easy to find.
The constellation Virgo the Maiden is easy to find by using the handle of the Big Dipper to arc to Arcturus in Boötes, then speeding on (spiking down) to Spica, Virgo’s brightest star. Image via EarthSky.
The constellation Virgo the Maiden
From the Northern Hemisphere, Virgo the Maiden appears high above the southern horizon on May evenings. And this is the best time of year to view this constellation, which is the largest of the zodiac. As a matter of fact, Virgo is also the 2nd-largest constellation overall, after Hydra. Plus, thanks to its brightest star, Spica, there’s an easy trick to finding this constellation.
So, to find Virgo, remember this handy mnemonic device: Arc to Arcturus and speed on (spike) to Spica. What does that mean? Using the readily identifiable Big Dipper, you can follow the curve of its handle as you arc to a bright orangish star named Arcturus in the constellation Boötes. Then “drive a spike” (or sometimes the saying is “speed on down”) to Spica.
Spica is a blue-white, 1st-magnitude star near the center of Virgo.
First, follow the curve in the Big Dipper’s handle to the bright orange star Arcturus. Then extend that line to Spica. To be sure you’ve found Spica, look for a lopsided square pattern nearby: that’s Corvus the Crow. Image via Chelynne Campion.
The stars of the Maiden
Spica, which marks a bundle of wheat that the Maiden is holding, is the 15th brightest star in the sky. Spica is a magnitude 1.04 star that lies 250 light-years from Earth.
Then the next brightest star in Virgo is the binary star Gamma Virginis, or Porrima. Porrima is magnitude 2.74 and lies near the center of the constellation, above (northwest of) Spica. It lies 38 light-years away. Next, the 3rd brightest star is at the northern reaches of the constellation. Vindemiatrix is a magnitude 2.82 star located 109 light-years away.
Virgo the Maiden and its stars. Image via the International Astronomical Union (IAU).Here’s a classical illustration of the constellation Virgo the Maiden, via Urania’s Mirror/ Wikipedia (public domain).
The Virgo Cluster
Virgo is famous for its thousands of galaxies. One grouping – the Virgo Cluster – is near the border with Coma Berenices, west of Vindemiatrix. The Virgo Cluster is the nearest large group of galaxies to the Milky Way. The Virgo Cluster lies at the center of the Local Supercluster, a massive group containing clusters of galaxies. The Local Group of galaxies, which includes the Milky Way, is also part of the Local Supercluster.
Additionally, the gravitational pull from the Virgo Cluster in the Local Supercluster is slowing the escape velocity of the Milky Way and our Local Group. So the Virgo cluster is one of the few places in the universe we are speeding toward. Therefore, the galaxies in the Virgo Cluster are some of the few we see with a blueshift instead of a redshift. One day, these many galaxies will merge into one huge conglomeration.
In fact, the galaxy with one of the highest blueshifts lies right on the border of Virgo and Coma Berenices. This galaxy, M90, is moving rapidly among the other objects in the Virgo Cluster. That’s because it’s also being stripped of gas and dust due to its close quarters with the other galaxies. At magnitude 9.5, you can see this galaxy in a telescope across the 60 million light-year span.
In addition, other galaxies between 8th and 9th magnitude in this location are M49, M58, M59, M60, M84, M86, M87, and M89. Even more galaxies come into view if you scan along the line between Virgo and Coma Berenices.
M87 is a special galaxy that deserves to be singled out from the Virgo Cluster. It shines at magnitude 8.6 and is therefore easy to detect in any telescope and even in some binoculars. M87 lies about 60 million light-years away. Its potato-shaped clump of stars extends well over half a million light-years across. Additionally, it is thought to be five times the size of the Milky Way’s diameter. However, the diameter of the galaxy’s halo is about a million light-years, and while that is large, astronomers expected it to be even larger. They believe something cut the halo off early on in M87’s formation.
In fact, M87 is home to the largest known number of globular clusters. For comparison, the Milky Way has about 200 globulars, while M87 has thousands. These clusters may be dwarf galaxies that M87’s gravitation sucked in.
Another amazing feature of M87 is its jet that extends outward from the core for thousands of light-years. A monster black hole at the galaxy’s core is the source of the jet. In fact, M87’s black hole was the 1st ever imaged, in 2019. Then, recently that image was enhanced and released with more detail in April 2023. Plus, its black hole and its jet were imaged together for 1st time ever in April 2023.
View larger. | An optical light image of the jet erupting from the black hole at the core of galaxy Messier 87 (M87 or NGC 4486). The Hubble Space Telescope took this image on July 6, 2000. Image via NASA/ The Hubble Heritage Team (STScI/AURA)/ Wikimedia Commons (public doman).
The Sombrero Galaxy
Not to be overlooked is another bright and notable galaxy that’s apart from the large cluster: M104, or the Sombrero Galaxy. It’s located on the southeastern border of the constellation with Corvus the Crow. Without a doubt, M104 is a stunning galaxy in photographs. Even better, at magnitude 8.3, you can see it in small telescopes. It’s an edge-on, dusty spiral galaxy with a bright core. M104 lies approximately 55 million light-years away.
M104, or the Sombrero Galaxy, lies in the constellation Virgo the Maiden. Image via ESA/ Hubblesite/ Wikimedia Commons (public domain).
Virgo in mythology
The constellation Virgo is linked to the myth of Demeter, the harvest goddess, and her daughter Persephone. According to the myth, it once was always springtime on Earth. But then the god of the underworld, Hades, kidnapped Persephone.
Demeter, overcome with grief, abandoned her role as an Earth goddess. The world’s fruitfulness and fertility suffered. So Zeus insisted that Hades return Persephone to Demeter. But Zeus set a condition. He said Persephone must not eat until she returned to her home. That’s when Hades gave Persephone a pomegranate. It’s said that Persephone ate just six seeds.
So Persephone returned to her mother. But – because of the pomegranate – she has to return to the underworld for half of every year. To this day, spring returns to the Northern Hemisphere when Persephone reunites with Demeter. Then the winter season reigns when Persephone dwells in the underworld. Considering this, from the perspective of the Northern Hemisphere, Virgo is absent from early evening sky in late autumn, winter and early spring. Virgo’s return to the sky at nightfall – in the months of April and May – coincides with the season of spring.
The Return of Persephone” rel=”noopener” target=”_blank”>Persephone by Frederic Leighton. Image via Wikipedia (public domain).
Bottom line: Virgo the Maiden is the largest of the zodiac constellations. A handy mnemonic device – using the Big Dipper and its bright star Spica – make it easy to find.
View larger. | The Juno spacecraft captured this view of Jupiter’s moon Europa during its closest-ever flyby on September 29, 2022. The images reveal new clues about the moon’s ice crust. It seems it floats on the ocean below it! Image via NASA JPL-Caltech/ SwRI/ MSSS/ Björn Jónsson.
NASA’s Juno mission has provided images and new details about Jupiter’s ocean moon Europa.
The findings suggest the moon’s ice shell floats on top of the ocean and can move around in a process called true polar wander.
The images also reveal more evidence for previous water vapor plumes that left cryovolcanic deposits on Europa’s surface and places where watery brines may have trickled up to the surface.
Space fans are eagerly awaiting the upcoming Europa Clipper mission, which will provide our closest look yet at Europa, Jupiter’s intriguing ocean moon. It’ll launch this coming fall. In the meantime, scientists have been analyzing some new high-definition images from the Juno spacecraft, which has been orbiting Jupiter since 2016. NASA said on May 15, 2024, that Juno didn’t detect any active plumes of liquid on Europa, like those we see on Saturn’s moon Enceladus. But the newly-released images do support the hypothesis that Europa’s crust is free-floating on an ocean below. And they show signs of deposits from ice volcanoes (cryovolcanoes) on the surface from possible earlier water vapor plumes. Plus there’s a “disappearing crater” and an unusual “platypus”-shaped feature.
Juno obtained these images on September 29, 2022. They’re the closest ones yet of Europa. The peer-reviewed results are presented in two new papers, one in The Planetary Science Journal (March 21, 2024) and the other in JGR Planets (December 22, 2023).
The JunoCam instrument took four of the images and the Stellar Reference Unit (SRU) obtained one image. Juno came within 220 miles (355 kilometers) of the moon’s frozen, icy surface.
Free-floating ice shell
One big finding is that the images support the theory that Europa has experienced true polar wander. The theory states that Europa’s ice crust is free-floating on top of the ocean below. That means the ice shell can move. The images showed irregularly distributed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) wide. The depressions resemble large ovoid pits previously that scientists have seen in imagery from other locations on Europa.
Candy Hansen is the lead author of the first paper, at the Planetary Science Institute in Tucson, Arizona. She said:
True polar wander occurs if Europa’s icy shell is decoupled from its rocky interior, resulting in high stress levels on the shell, which lead to predictable fracture patterns. This is the first time that these fracture patterns have been mapped in the southern hemisphere, suggesting that true polar wander’s effect on Europa’s surface geology is more extensive than previously identified.
Disappearing crater
Gwern crater was thought to be one of the few craters visible on Europa’s surface, about 13 miles (21 km) across. But the new Juno images revealed it to be an illusion. As Hansen explained:
Crater Gwern is no more. What was once thought to be a 13-mile-wide impact crater – one of Europa’s few documented impact craters – Gwern was revealed in JunoCam data to be a set of intersecting ridges that created an oval shadow.
As a result, the number of known craters larger than one km on Europa is now 40 instead of 41.
View larger. | This Juno image shows the Platypus region (in yellow rectangle) and double ridges with stains thought to be deposits from water vapor plumes (blue rectangle). Image via NASA (CC BY 4.0).
The Platypus
One of the intriguing features seen in the images is nicknamed the Platypus, given its shape. It’s 23 miles (37 km) wide by 42 miles (68 km) long and geologically younger than the surrounding terrain. It is an area of chaos terrain, featuring hummocks, ridges, and dark reddish-brown material inside it. The “torso” and “bill” are connected by a “neck” that is fractured. There are also many ice blocks ranging from 0.6 to 4.3 miles (1 to 7 km) wide.
The researchers said that this may be an area where briny water from below has reached the surface. The paper stated:
Although its topographic context is not well understood due to the absence of stereo for this region, our morphological findings from shape-from-shading and visual interpretation are consistent with multiple predictions made by the melt lens model for chaos formation. That model predicts the presence of subsurface liquid, and ongoing formation activity in features where surface ice subsides and ice blocks float below the surrounding terrain.
Plume deposits in images of Europa?
Scientists have previously seen hints of water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus. They seem to be smaller and less frequent, however. Another feature in the Juno images supports the plume hypothesis. It is a set of double ridges flanked by dark stains, about 31 miles (50 km) north of the Platypus. It is an ideal target for NASA’s upcoming Europa Clipper mission and the ESA’s Jupiter Icy Moons (Juice) mission. Heidi Becker, lead co-investigator for the SRU at NASA’s Jet Propulsion Laboratory in Southern California, said:
The SRU’s image is a high-quality baseline for specific places NASA’s Europa Clipper mission and ESA’s (European Space Agency’s) Juice mission can target to search for signs of change and brine.
Juno did not detect any signs of current plume activity during its observations. That doesn’t mean there aren’t any eruptions happening at all though, as the paper noted:
However, an eruption would have to occur at just the right longitude (limb or terminator) and just the right time when Juno flew by, so the probability of a detection was never very high
View larger. | Juno image of Gwern crater (right) compared with older Galileo image (left). The new view revealed that it isn’t actually a crater at all, but a set of intersecting ridges. Image via Hansen et al./ The Planetary Science Journal/ NASA (CC BY 4.0).
Europa Clipper and Juice
Europa Clipper, as the name implies, will focus on Europa, making numerous close flybys of the moon. It will reveal more details about both Europa’s surface and subsurface ocean. It will launch later this year and arrive in 2030.
ESA’s Jupiter Icy Moons Explorer (Juice) is already on its way to Jupiter, launched on April 14, 2023. It will reach Jupiter in July 2031. Unlike Europa Clipper, it will study Jupiter, its rings and numerous moons, with a focus on the largest moon, Ganymede.
Juno has already conducted 61 close flybys of Jupiter itself, the latest being on May 12, 2024. The next one will be on June 13, where the spacecraft will also come to within 18,200 miles (29,300 km) of the volcanic moon Io. Launched on August 5, 2011, Juno has been exploring Jupiter and its moons since 2016. Its primary mission is to study the giant planet’s atmosphere and interior, but it does sometimes conduct flybys of some the larger moons as well.
Bottom line: NASA has released some images of Europa, the ocean moon of Jupiter. They provide new clues about the moon’s ice shell and other intriguing surface features.
View larger. | The Juno spacecraft captured this view of Jupiter’s moon Europa during its closest-ever flyby on September 29, 2022. The images reveal new clues about the moon’s ice crust. It seems it floats on the ocean below it! Image via NASA JPL-Caltech/ SwRI/ MSSS/ Björn Jónsson.
NASA’s Juno mission has provided images and new details about Jupiter’s ocean moon Europa.
The findings suggest the moon’s ice shell floats on top of the ocean and can move around in a process called true polar wander.
The images also reveal more evidence for previous water vapor plumes that left cryovolcanic deposits on Europa’s surface and places where watery brines may have trickled up to the surface.
Space fans are eagerly awaiting the upcoming Europa Clipper mission, which will provide our closest look yet at Europa, Jupiter’s intriguing ocean moon. It’ll launch this coming fall. In the meantime, scientists have been analyzing some new high-definition images from the Juno spacecraft, which has been orbiting Jupiter since 2016. NASA said on May 15, 2024, that Juno didn’t detect any active plumes of liquid on Europa, like those we see on Saturn’s moon Enceladus. But the newly-released images do support the hypothesis that Europa’s crust is free-floating on an ocean below. And they show signs of deposits from ice volcanoes (cryovolcanoes) on the surface from possible earlier water vapor plumes. Plus there’s a “disappearing crater” and an unusual “platypus”-shaped feature.
Juno obtained these images on September 29, 2022. They’re the closest ones yet of Europa. The peer-reviewed results are presented in two new papers, one in The Planetary Science Journal (March 21, 2024) and the other in JGR Planets (December 22, 2023).
The JunoCam instrument took four of the images and the Stellar Reference Unit (SRU) obtained one image. Juno came within 220 miles (355 kilometers) of the moon’s frozen, icy surface.
Free-floating ice shell
One big finding is that the images support the theory that Europa has experienced true polar wander. The theory states that Europa’s ice crust is free-floating on top of the ocean below. That means the ice shell can move. The images showed irregularly distributed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) wide. The depressions resemble large ovoid pits previously that scientists have seen in imagery from other locations on Europa.
Candy Hansen is the lead author of the first paper, at the Planetary Science Institute in Tucson, Arizona. She said:
True polar wander occurs if Europa’s icy shell is decoupled from its rocky interior, resulting in high stress levels on the shell, which lead to predictable fracture patterns. This is the first time that these fracture patterns have been mapped in the southern hemisphere, suggesting that true polar wander’s effect on Europa’s surface geology is more extensive than previously identified.
Disappearing crater
Gwern crater was thought to be one of the few craters visible on Europa’s surface, about 13 miles (21 km) across. But the new Juno images revealed it to be an illusion. As Hansen explained:
Crater Gwern is no more. What was once thought to be a 13-mile-wide impact crater – one of Europa’s few documented impact craters – Gwern was revealed in JunoCam data to be a set of intersecting ridges that created an oval shadow.
As a result, the number of known craters larger than one km on Europa is now 40 instead of 41.
View larger. | This Juno image shows the Platypus region (in yellow rectangle) and double ridges with stains thought to be deposits from water vapor plumes (blue rectangle). Image via NASA (CC BY 4.0).
The Platypus
One of the intriguing features seen in the images is nicknamed the Platypus, given its shape. It’s 23 miles (37 km) wide by 42 miles (68 km) long and geologically younger than the surrounding terrain. It is an area of chaos terrain, featuring hummocks, ridges, and dark reddish-brown material inside it. The “torso” and “bill” are connected by a “neck” that is fractured. There are also many ice blocks ranging from 0.6 to 4.3 miles (1 to 7 km) wide.
The researchers said that this may be an area where briny water from below has reached the surface. The paper stated:
Although its topographic context is not well understood due to the absence of stereo for this region, our morphological findings from shape-from-shading and visual interpretation are consistent with multiple predictions made by the melt lens model for chaos formation. That model predicts the presence of subsurface liquid, and ongoing formation activity in features where surface ice subsides and ice blocks float below the surrounding terrain.
Plume deposits in images of Europa?
Scientists have previously seen hints of water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus. They seem to be smaller and less frequent, however. Another feature in the Juno images supports the plume hypothesis. It is a set of double ridges flanked by dark stains, about 31 miles (50 km) north of the Platypus. It is an ideal target for NASA’s upcoming Europa Clipper mission and the ESA’s Jupiter Icy Moons (Juice) mission. Heidi Becker, lead co-investigator for the SRU at NASA’s Jet Propulsion Laboratory in Southern California, said:
The SRU’s image is a high-quality baseline for specific places NASA’s Europa Clipper mission and ESA’s (European Space Agency’s) Juice mission can target to search for signs of change and brine.
Juno did not detect any signs of current plume activity during its observations. That doesn’t mean there aren’t any eruptions happening at all though, as the paper noted:
However, an eruption would have to occur at just the right longitude (limb or terminator) and just the right time when Juno flew by, so the probability of a detection was never very high
View larger. | Juno image of Gwern crater (right) compared with older Galileo image (left). The new view revealed that it isn’t actually a crater at all, but a set of intersecting ridges. Image via Hansen et al./ The Planetary Science Journal/ NASA (CC BY 4.0).
Europa Clipper and Juice
Europa Clipper, as the name implies, will focus on Europa, making numerous close flybys of the moon. It will reveal more details about both Europa’s surface and subsurface ocean. It will launch later this year and arrive in 2030.
ESA’s Jupiter Icy Moons Explorer (Juice) is already on its way to Jupiter, launched on April 14, 2023. It will reach Jupiter in July 2031. Unlike Europa Clipper, it will study Jupiter, its rings and numerous moons, with a focus on the largest moon, Ganymede.
Juno has already conducted 61 close flybys of Jupiter itself, the latest being on May 12, 2024. The next one will be on June 13, where the spacecraft will also come to within 18,200 miles (29,300 km) of the volcanic moon Io. Launched on August 5, 2011, Juno has been exploring Jupiter and its moons since 2016. Its primary mission is to study the giant planet’s atmosphere and interior, but it does sometimes conduct flybys of some the larger moons as well.
Bottom line: NASA has released some images of Europa, the ocean moon of Jupiter. They provide new clues about the moon’s ice shell and other intriguing surface features.
