Freezing rain: All about this dangerous ice

Freezing rain leaves a thick coat of ice on a tree branch. Image via Wikimedia Commons.

Freezing rain

Freezing rain is simply rain that falls through a shallow layer of cold temperatures at or below 32 degrees Fahrenheit (0 degrees Celsius) near the surface. When this rain becomes super-cooled, it can freeze on contact with roads, bridges, trees, power lines and vehicles. When freezing rain accumulates, it can add a lot of weight on trees – a quarter of an inch of ice can add 500 pounds of weight – which can bring trees down and result in numerous power outages and damage to homes.

Freezing rain is typically the weather threat that creates the most car accidents, injuries and deaths in winter storms. Many people can drive in the rain and snow, but when the roads become icy, it is almost impossible to drive. Severe ice storms can shut down large cities, result in thousands of power outages, and the most severe ones can also become billion-dollar disasters (rare).

This chart shows how snow melts as it falls through the air and becomes freezing rain when it nears the surface. Image via NWS.

Available now! 2025 EarthSky lunar calendar. A unique and beautiful poster-sized calendar showing phases of the moon every night of the year! And it makes a great gift.

Different types of winter precipitation

It is important to know the difference between snow, sleet and freezing rain.

1) Snow forms when the entire layer of air is sub-freezing. Snow consists of ice crystals and is white and fluffy.

2) Sleet forms when the layer of sub-freezing air is fairly deep at 3,000 to 4,000 feet. This allows time for the water droplet to freeze into a tiny piece of ice and become sleet as it falls to the surface. Precipitation in the wintertime that falls as tiny ice pellets is sleet. Hail is only associated with strong thunderstorms and are larger in size and can cause damage.

3) Freezing rain forms when the sub-freezing layer is very shallow. At 2,000 feet from the surface, temperatures are above freezing, so any precipitation that falls is liquid. Once rain hits that shallow, cold air near the surface, it freezes on contact with any object.

Shallow, cold air at the surface can sometimes occur thanks to cold air damming. Cold air damming, abbreviated as CAD, is where a low-level cold air mass becomes trapped topographically. These events can be very common near or around mountain regions, and is known to occur across the eastern United States thanks to the Appalachian Mountains. Some of the worst ice storms to form were thanks to this CAD effect that is also known as the “wedge”. This term is used because shallow cold air is wedged down the Appalachian Mountains thanks to a ridge of high pressure typically located across New England, eastern Canada, or the Mid-Atlantic.

This chart shows temperatures and types of winter precipitation. They are snow, sleet, freezing rain and rain. Image via NWS.

Freezing rain causes major problems

When it comes to freezing rain, it is the weight of the ice on the trees that causes problems. They can fall over and crush cars, houses and power lines. According to Steve Nix, brittle tree species typically take the brunt of heavy icing. Trees such as poplars, silver maples, birches, willows and hack-berries are more likely to break and fall over due to the weight of the ice. One of the big reasons these trees break and fall over first is because they are fast growers. They also develop weak, V-shaped crotches that can easily split apart under the added weight of ice.

View at EarthSky Community Photos. | Carol Henderson captured freezing rain on this bush in Durham, North Carolina, on January 10, 2025. Thank you, Carol!

View at EarthSky Community Photos. | Nina Gorenstein in West Lafayette, Indiana, captured this photo of ice coating the neighborhood. She wrote: “The New Year began with wind and freezing rain alerts. Ice crust and frozen rain drops appeared on branches of trees, wires, borders of roofs. The tiny icicles are so evenly distributed!” Thanks, Nina!

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Bottom line: Freezing rain is simply rain that falls into a shallow layer of cold temperatures that is below freezing. When this super-cooled droplet hits an object, it then freezes and becomes ice. Freezing ice is dangerous and can down power lines, paralyze cities, bring down trees and cause serious accidents.

Read more: Too cold to snow? Is that possible?

The post Freezing rain: All about this dangerous ice first appeared on EarthSky.

from EarthSky https://ift.tt/p2qHZBM

Freezing rain leaves a thick coat of ice on a tree branch. Image via Wikimedia Commons.

Freezing rain

Freezing rain is simply rain that falls through a shallow layer of cold temperatures at or below 32 degrees Fahrenheit (0 degrees Celsius) near the surface. When this rain becomes super-cooled, it can freeze on contact with roads, bridges, trees, power lines and vehicles. When freezing rain accumulates, it can add a lot of weight on trees – a quarter of an inch of ice can add 500 pounds of weight – which can bring trees down and result in numerous power outages and damage to homes.

Freezing rain is typically the weather threat that creates the most car accidents, injuries and deaths in winter storms. Many people can drive in the rain and snow, but when the roads become icy, it is almost impossible to drive. Severe ice storms can shut down large cities, result in thousands of power outages, and the most severe ones can also become billion-dollar disasters (rare).

This chart shows how snow melts as it falls through the air and becomes freezing rain when it nears the surface. Image via NWS.

Available now! 2025 EarthSky lunar calendar. A unique and beautiful poster-sized calendar showing phases of the moon every night of the year! And it makes a great gift.

Different types of winter precipitation

It is important to know the difference between snow, sleet and freezing rain.

1) Snow forms when the entire layer of air is sub-freezing. Snow consists of ice crystals and is white and fluffy.

2) Sleet forms when the layer of sub-freezing air is fairly deep at 3,000 to 4,000 feet. This allows time for the water droplet to freeze into a tiny piece of ice and become sleet as it falls to the surface. Precipitation in the wintertime that falls as tiny ice pellets is sleet. Hail is only associated with strong thunderstorms and are larger in size and can cause damage.

3) Freezing rain forms when the sub-freezing layer is very shallow. At 2,000 feet from the surface, temperatures are above freezing, so any precipitation that falls is liquid. Once rain hits that shallow, cold air near the surface, it freezes on contact with any object.

Shallow, cold air at the surface can sometimes occur thanks to cold air damming. Cold air damming, abbreviated as CAD, is where a low-level cold air mass becomes trapped topographically. These events can be very common near or around mountain regions, and is known to occur across the eastern United States thanks to the Appalachian Mountains. Some of the worst ice storms to form were thanks to this CAD effect that is also known as the “wedge”. This term is used because shallow cold air is wedged down the Appalachian Mountains thanks to a ridge of high pressure typically located across New England, eastern Canada, or the Mid-Atlantic.

This chart shows temperatures and types of winter precipitation. They are snow, sleet, freezing rain and rain. Image via NWS.

Freezing rain causes major problems

When it comes to freezing rain, it is the weight of the ice on the trees that causes problems. They can fall over and crush cars, houses and power lines. According to Steve Nix, brittle tree species typically take the brunt of heavy icing. Trees such as poplars, silver maples, birches, willows and hack-berries are more likely to break and fall over due to the weight of the ice. One of the big reasons these trees break and fall over first is because they are fast growers. They also develop weak, V-shaped crotches that can easily split apart under the added weight of ice.

View at EarthSky Community Photos. | Carol Henderson captured freezing rain on this bush in Durham, North Carolina, on January 10, 2025. Thank you, Carol!

View at EarthSky Community Photos. | Nina Gorenstein in West Lafayette, Indiana, captured this photo of ice coating the neighborhood. She wrote: “The New Year began with wind and freezing rain alerts. Ice crust and frozen rain drops appeared on branches of trees, wires, borders of roofs. The tiny icicles are so evenly distributed!” Thanks, Nina!

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: Freezing rain is simply rain that falls into a shallow layer of cold temperatures that is below freezing. When this super-cooled droplet hits an object, it then freezes and becomes ice. Freezing ice is dangerous and can down power lines, paralyze cities, bring down trees and cause serious accidents.

Read more: Too cold to snow? Is that possible?

The post Freezing rain: All about this dangerous ice first appeared on EarthSky.

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Spiders can smell using their legs! The secret uncovered

A new discovery said spiders can smell using their legs. Scientists from Lund University in Sweden and the University of Greifswald in Germany analyzed wasp spiders (Argiope bruennichi) and discovered olfactory hairs on their legs. Image via Lucas van Oort/ Unsplash.

Spiders can smell using their legs

A team of researchers from Lund University in Sweden and the University of Greifswald in Germany found some male spiders use olfactory hairs on their legs to distantly detect sexual pheromones that female spiders release. These olfactory hairs had been overlooked until now. The Conversation wrote an article about the discovery on January 7, 2024.

There are more than 45,000 species of spiders in the world. And these creatures have inhabited Earth for 400 billion years. However, although scientists knew these eight-legged beings could detect odors, they didn’t know how, exactly. The researchers published their study in the journal Proceedings of the National Academy of Sciences on January 6, 2025.

The 2025 EarthSky lunar calendar makes a great gift. Get yours today!

How did they make the discovery?

Spiders do not have nostrils like mammals. Neither do they have antennae like insects, which have olfactory hairs called wall-pore sensilla on their antennae. Insects use these hairs to smell. Previous studies suggested spiders do not have wall-pore sensilla.

However, the researchers in the new study looked at male wasp spiders (Argiope bruennichi). They found the males do indeed have wall-pore sensilla on their legs. You could say these males smell with their legs.

Also, this is not an ability specific to wasp spiders, but rather it’s a capacity prevalent for all (male) spiders.

Some adult male spiders have olfactory hairs called wall-pore sensilla on the upper part of their legs. These hairs detect sexual pheromones that females produce. Image via Mohammad Belal Talukder, Carsten H. G. Müller, Dan-Dan Zhang and Gabriele B. Uhl/ PNAS.

What is the sense of smell like in spiders?

Scientists studied both male and female spiders of the Argiope bruennichi species. The team used high-resolution scanning electron microscopy and discovered something fascinating. Male spiders have wall-pore sensilla on all eight legs. What’s more, these sensilla are different from the sensilla found in insects and even other arthropods.

The wall-pore sensilla in males are located on the top of the legs, that is, close to the body. These areas almost never come into contact with a surface when spiders move. And, interestingly, the wall-pore sensilla have only been found in adult males. Neither young males nor females have these hairs.

External appearance and cross-sections of wall-pore sensilla in Argiope bruennichi males. Image via Mohammad Belal Talukder, Carsten H. G. Müller, Dan-Dan Zhang and Gabriele B. Uhl/ PNAS.

What about female spiders?

Scientists believe male spiders use wall-pore sensilla to detect airborne sex pheromones released by females. This is supposedly how these males find mates. Female spiders release gaseous pheromones that attract males from a distance.

To prove their theory, the scientists placed male spiders under a microscope and connected electrodes to the wall-pore sensilla. When the male spiders were exposed to a pheromone compound, even in a very small amount, the spiders responded with a burst of activity in neuronal cells from the sensilla.

The scientists observed how their olfactory sensilla are incredibly sensitive, much more so than the most sensitive sex pheromone communication systems in insects.

What’s next?

The scientists analyzed 19 other spider species and found that most have wall-pore sensilla and that they are specific to males.

However, other spider species, such as the basal trapdoor spider, do not have these olfactory hairs. The wall-pore sensilla evolved independently within spiders and were lost in some lineages.

Many questions remain to be answered by future studies: Can female spiders and young males smell in another way? How many other species have these olfactory hairs? Can species that do not have these hairs smell in another way? Can spiders detect other chemicals besides sexual pheromones?

It will be exciting to see what new discoveries can tell us.

Bottom line: Scientists knew spiders could smell, but they didn’t know how, exactly. Until now. Spiders can smell using their legs. But, interestingly, young male spiders and female spiders don’t possess this ability. Find out why, here.

Via The Conversation

Source: PNAS: Olfaction with legs—Spiders use wall-pore sensilla for pheromone detection

Read more: Here are 3 amazing feats of spiders

Read more: Lifeform of the week: Scorpions

The post Spiders can smell using their legs! The secret uncovered first appeared on EarthSky.

from EarthSky https://ift.tt/whODAcE

A new discovery said spiders can smell using their legs. Scientists from Lund University in Sweden and the University of Greifswald in Germany analyzed wasp spiders (Argiope bruennichi) and discovered olfactory hairs on their legs. Image via Lucas van Oort/ Unsplash.

Spiders can smell using their legs

A team of researchers from Lund University in Sweden and the University of Greifswald in Germany found some male spiders use olfactory hairs on their legs to distantly detect sexual pheromones that female spiders release. These olfactory hairs had been overlooked until now. The Conversation wrote an article about the discovery on January 7, 2024.

There are more than 45,000 species of spiders in the world. And these creatures have inhabited Earth for 400 billion years. However, although scientists knew these eight-legged beings could detect odors, they didn’t know how, exactly. The researchers published their study in the journal Proceedings of the National Academy of Sciences on January 6, 2025.

The 2025 EarthSky lunar calendar makes a great gift. Get yours today!

How did they make the discovery?

Spiders do not have nostrils like mammals. Neither do they have antennae like insects, which have olfactory hairs called wall-pore sensilla on their antennae. Insects use these hairs to smell. Previous studies suggested spiders do not have wall-pore sensilla.

However, the researchers in the new study looked at male wasp spiders (Argiope bruennichi). They found the males do indeed have wall-pore sensilla on their legs. You could say these males smell with their legs.

Also, this is not an ability specific to wasp spiders, but rather it’s a capacity prevalent for all (male) spiders.

Some adult male spiders have olfactory hairs called wall-pore sensilla on the upper part of their legs. These hairs detect sexual pheromones that females produce. Image via Mohammad Belal Talukder, Carsten H. G. Müller, Dan-Dan Zhang and Gabriele B. Uhl/ PNAS.

What is the sense of smell like in spiders?

Scientists studied both male and female spiders of the Argiope bruennichi species. The team used high-resolution scanning electron microscopy and discovered something fascinating. Male spiders have wall-pore sensilla on all eight legs. What’s more, these sensilla are different from the sensilla found in insects and even other arthropods.

The wall-pore sensilla in males are located on the top of the legs, that is, close to the body. These areas almost never come into contact with a surface when spiders move. And, interestingly, the wall-pore sensilla have only been found in adult males. Neither young males nor females have these hairs.

External appearance and cross-sections of wall-pore sensilla in Argiope bruennichi males. Image via Mohammad Belal Talukder, Carsten H. G. Müller, Dan-Dan Zhang and Gabriele B. Uhl/ PNAS.

What about female spiders?

Scientists believe male spiders use wall-pore sensilla to detect airborne sex pheromones released by females. This is supposedly how these males find mates. Female spiders release gaseous pheromones that attract males from a distance.

To prove their theory, the scientists placed male spiders under a microscope and connected electrodes to the wall-pore sensilla. When the male spiders were exposed to a pheromone compound, even in a very small amount, the spiders responded with a burst of activity in neuronal cells from the sensilla.

The scientists observed how their olfactory sensilla are incredibly sensitive, much more so than the most sensitive sex pheromone communication systems in insects.

What’s next?

The scientists analyzed 19 other spider species and found that most have wall-pore sensilla and that they are specific to males.

However, other spider species, such as the basal trapdoor spider, do not have these olfactory hairs. The wall-pore sensilla evolved independently within spiders and were lost in some lineages.

Many questions remain to be answered by future studies: Can female spiders and young males smell in another way? How many other species have these olfactory hairs? Can species that do not have these hairs smell in another way? Can spiders detect other chemicals besides sexual pheromones?

It will be exciting to see what new discoveries can tell us.

Bottom line: Scientists knew spiders could smell, but they didn’t know how, exactly. Until now. Spiders can smell using their legs. But, interestingly, young male spiders and female spiders don’t possess this ability. Find out why, here.

Via The Conversation

Source: PNAS: Olfaction with legs—Spiders use wall-pore sensilla for pheromone detection

Read more: Here are 3 amazing feats of spiders

Read more: Lifeform of the week: Scorpions

The post Spiders can smell using their legs! The secret uncovered first appeared on EarthSky.

from EarthSky https://ift.tt/whODAcE

Little Red Dots might indicate ancient, growing black holes

Here are a few of many mysterious Little Red Dots, that the Webb space telescope spotted in parts of the sky. They have perplexed researchers since astronomers first noticed them, in 2022. But, having compiled one of the largest samples of Little Red Dots yet, a team of researchers says a large fraction of them are likely galaxies with black holes growing at their centers. Image via NASA, ESA, CSA, STScI, Dale Kocevski (Colby College).

NASA published this article on January 14, 2025. Edits by EarthSky.

What are Webb’s mysterious Little Red Dots?

In December 2022, less than six months after commencing science operations, NASA’s James Webb Space Telescope revealed something never seen before. It discovered an abundance of tiny red objects scattered across the sky. Scientists dubbed them ‘Little Red Dots.’ Since then, researchers have been perplexed by their nature, the reason for their color and what they convey about the early universe.

Now, a team of astronomers has compiled one of the largest samples of Little Red Dots to date. Nearly all of them existed during the first 1.5 billion years after the Big Bang. And they said on January 14, 2025, that a large fraction of the Little Red Dots in their sample are likely galaxies with supermassive black holes growing at their centers.

2025 EarthSky lunar calendar is available now. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

A peek into early black hole growth?

By combing through data from several publicly available surveys, the researchers assembled a huge sample of these Little Red Dots. And they found the distribution of these objects across time to be intriguing. The Little Red Dots appear to emerge in large numbers around 600 million years after the Big Bang. They then underwent a rapid decline in quantity around 1.5 billion years after the Big Bang.

And they found that about 70 percent of the targets showed evidence for gas rapidly orbiting 2 million miles per hour (900 kilometers per second). That’s what you’d expect from an accretion disk around a supermassive black hole. So this suggests many Little Red Dots are accreting black holes, also known as active galactic nuclei (AGN).

Steven Finkelstein, a co-author of the study, said:

The most exciting thing for me is the redshift distributions. These really red, high-redshift sources basically stop existing at a certain point after the big bang. If they are growing black holes, and we think at least 70 percent of them are, this hints at an era of obscured [by gas and dust] black hole growth in the early universe.

A montage of some of the intriguing Little Red Dots Webb has spotted in the early universe. Image via J. Matthee et al., 2024 (CC BY 4.0).

Contrary to headlines, cosmology isn’t broken

When astronomers first discovered the Little Red Dots, some suggested that cosmology was ‘broken.’ If all of the light coming from these objects was from stars, it implied that some galaxies had grown so big, so fast, that theories could not account for them.

But the team’s research suggests that much of the light coming from these objects is from accreting black holes, not from stars. Fewer stars means smaller, more lightweight galaxies existing theories can explain.

Anthony Taylor, a co-author of the study, surmised:

This is how you solve the universe-breaking problem.

But questions remain around Little Red Dots

But the Little Red Dots evoke even more questions. For example, it’s still not clear why they don’t appear at lower redshifts. That is, more recently in the universe’s history. One possible answer is inside-out growth. As star formation within a galaxy expands outward from the nucleus, supernovae deposit less gas near the accreting black hole. It then becomes less obscured. So the black hole eventually sheds its gas cocoon, becoming bluer and less red. It therefore stops appearing as a Little Red Dot.

Additionally, Little Red Dots are not bright in X-ray light, unlike most black holes we see in the more recent universe. However, astronomers know that at certain gas densities, X-ray photons can become trapped. This reduces the amount of X-ray emission. Therefore, this quality of Little Red Dots could support the theory that these are heavily obscured black holes.

The team is taking multiple approaches to understand the nature of Little Red Dots. This includes examining the mid-infrared properties of their sample, and looking more broadly for accreting black holes to see how many fit the Little Red Dots criteria. Obtaining deeper follow-up observations will also be beneficial for solving this currently ‘open case’ about the mysterious Little Red Dots.

The researchers presented these results in a press conference at the 245th meeting of the American Astronomical Society in National Harbor, Maryland. They have also been submitted for publication in The Astrophysical Journal.

Bottom line: Researchers studying the mysterious Little Red Dots discovered by Webb have found evidence that they could be ancient galaxies with supermassive black holes growing at their centers.

Via NASA

Read more: 3 years of the Webb telescope: Here’s what it’s discovered

The post Little Red Dots might indicate ancient, growing black holes first appeared on EarthSky.

from EarthSky https://ift.tt/30csl4p

Here are a few of many mysterious Little Red Dots, that the Webb space telescope spotted in parts of the sky. They have perplexed researchers since astronomers first noticed them, in 2022. But, having compiled one of the largest samples of Little Red Dots yet, a team of researchers says a large fraction of them are likely galaxies with black holes growing at their centers. Image via NASA, ESA, CSA, STScI, Dale Kocevski (Colby College).

NASA published this article on January 14, 2025. Edits by EarthSky.

What are Webb’s mysterious Little Red Dots?

In December 2022, less than six months after commencing science operations, NASA’s James Webb Space Telescope revealed something never seen before. It discovered an abundance of tiny red objects scattered across the sky. Scientists dubbed them ‘Little Red Dots.’ Since then, researchers have been perplexed by their nature, the reason for their color and what they convey about the early universe.

Now, a team of astronomers has compiled one of the largest samples of Little Red Dots to date. Nearly all of them existed during the first 1.5 billion years after the Big Bang. And they said on January 14, 2025, that a large fraction of the Little Red Dots in their sample are likely galaxies with supermassive black holes growing at their centers.

2025 EarthSky lunar calendar is available now. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!

A peek into early black hole growth?

By combing through data from several publicly available surveys, the researchers assembled a huge sample of these Little Red Dots. And they found the distribution of these objects across time to be intriguing. The Little Red Dots appear to emerge in large numbers around 600 million years after the Big Bang. They then underwent a rapid decline in quantity around 1.5 billion years after the Big Bang.

And they found that about 70 percent of the targets showed evidence for gas rapidly orbiting 2 million miles per hour (900 kilometers per second). That’s what you’d expect from an accretion disk around a supermassive black hole. So this suggests many Little Red Dots are accreting black holes, also known as active galactic nuclei (AGN).

Steven Finkelstein, a co-author of the study, said:

The most exciting thing for me is the redshift distributions. These really red, high-redshift sources basically stop existing at a certain point after the big bang. If they are growing black holes, and we think at least 70 percent of them are, this hints at an era of obscured [by gas and dust] black hole growth in the early universe.

A montage of some of the intriguing Little Red Dots Webb has spotted in the early universe. Image via J. Matthee et al., 2024 (CC BY 4.0).

Contrary to headlines, cosmology isn’t broken

When astronomers first discovered the Little Red Dots, some suggested that cosmology was ‘broken.’ If all of the light coming from these objects was from stars, it implied that some galaxies had grown so big, so fast, that theories could not account for them.

But the team’s research suggests that much of the light coming from these objects is from accreting black holes, not from stars. Fewer stars means smaller, more lightweight galaxies existing theories can explain.

Anthony Taylor, a co-author of the study, surmised:

This is how you solve the universe-breaking problem.

But questions remain around Little Red Dots

But the Little Red Dots evoke even more questions. For example, it’s still not clear why they don’t appear at lower redshifts. That is, more recently in the universe’s history. One possible answer is inside-out growth. As star formation within a galaxy expands outward from the nucleus, supernovae deposit less gas near the accreting black hole. It then becomes less obscured. So the black hole eventually sheds its gas cocoon, becoming bluer and less red. It therefore stops appearing as a Little Red Dot.

Additionally, Little Red Dots are not bright in X-ray light, unlike most black holes we see in the more recent universe. However, astronomers know that at certain gas densities, X-ray photons can become trapped. This reduces the amount of X-ray emission. Therefore, this quality of Little Red Dots could support the theory that these are heavily obscured black holes.

The team is taking multiple approaches to understand the nature of Little Red Dots. This includes examining the mid-infrared properties of their sample, and looking more broadly for accreting black holes to see how many fit the Little Red Dots criteria. Obtaining deeper follow-up observations will also be beneficial for solving this currently ‘open case’ about the mysterious Little Red Dots.

The researchers presented these results in a press conference at the 245th meeting of the American Astronomical Society in National Harbor, Maryland. They have also been submitted for publication in The Astrophysical Journal.

Bottom line: Researchers studying the mysterious Little Red Dots discovered by Webb have found evidence that they could be ancient galaxies with supermassive black holes growing at their centers.

Via NASA

Read more: 3 years of the Webb telescope: Here’s what it’s discovered

The post Little Red Dots might indicate ancient, growing black holes first appeared on EarthSky.

from EarthSky https://ift.tt/30csl4p

Meet the Winter Circle, aka the Winter Hexagon

The Winter Circle or Winter Hexagon

The Winter Circle (or Hexagon) is a large circular pattern, made of some of the brightest stars in the Northern Hemisphere’s winter sky (or the Southern Hemisphere’s summer sky). It isn’t a constellation. It’s an asterism, or prominent group of stars that form a noticeable pattern. In addition, the Winter Circle has a smaller asterism inside it, called the Winter Triangle.

Plus in 2025 the planet Jupiter lies inside the Winter Circle and Mars is nearby.

The Winter Circle (or Winter Hexagon) isn’t a constellation. It’s an asterism, made of bright stars in the winter evening sky for the Northern Hemisphere (and summer sky for the Southern Hemisphere). It covers a large portion of the sky. Chart via EarthSky.

Meet the Winter Circle

Strictly speaking, you’ll see this circular pattern of 1st-magnitude stars – the brightest stars in our sky – from six different constellations: Rigel in Orion the Hunter, Aldebaran in Taurus the Bull, Capella in Auriga the Charioteer, Pollux (and its forever companion Castor) in Gemini the Twins, Procyon in Canis Minor the Lesser Dog and Sirius in Canis Major the Greater Dog. Also, an additional 1st-magnitude star, Betelgeuse in Orion the Hunter, lies toward the center of the Circle.

The Circle is big

The Winter Circle is big! To get an idea of the it’s humongous size, the span from the southernmost star, Sirius, to the northernmost star, Capella, covers about 1/3 of the dome of the sky.

Image of the evening sky on December 31, 2024, taken with an allsky camera. The Winter Hexagon takes up a large portion of the sky. Plus in 2025, the planets Jupiter and Mars are nearby. Image via WyoAstro observatory.

2025 lunar calendars on sale now. Makes a great gift! Check it out here.

When is the Winter Circle (or Hexagon) visible?

So, like all stars, those in the Winter Circle rise and set some four minutes earlier with each passing night. Indeed, by late January, the Winter Circle will have risen high enough above the northeastern horizon so it’s visible by about 7 p.m. local time. Then, if you look around midnight, the Winter Circle will be high above the southern horizon. And later, after about 3 a.m. local time, it sinks toward the southwestern horizon, with some of it setting in the west before sunrise.

Then, in late February and early March, the Winter Circle is in your southern sky at nightfall and early evening.

View at EarthSky Community Photos. | Jose Zarcos Palma in Mina Sao Domingo, Mertola, Portugal, took this image of the Winter Circle on December 26, 2022. Jose wrote: “I planned this composition to catch the great Winter Circle in an early stage of its ascension just behind the abandoned mining ruins of Achada do Gamo. We can clearly see Sirius in the Canis Major the Greater Dog near the chimney on the right side, just below Orion the Hunter. On top of the image, the planet Mars is near Aldebaran in Taurus the Bull.” Thank you, Jose!

Finding the Winter Circle

First, to find the Winter Circle (or Hexagon), find the easily recognizable constellation of Orion the Hunter. Indeed, its three belt stars give it away. Then, look for the bright bluish star to the lower right. This star is Rigel, the southwest corner of the Winter Circle and the first of the six stars in the Circle. By the way, Rigel is the brightest star in Orion and the seventh brightest star in the night sky.

Now draw a line through Orion’s Belt stars upward to find Aldebaran, the ruddy eye of Taurus the Bull. Aldebaran is the second star in the Circle and the brightest star in Taurus. As a matter of fact, Aldebaran is the fourteenth brightest star in the sky.

Next, continue upward in a counterclockwise direction to find the next bright star, Capella in Auriga the Charioteer. Capella is the third star on our journey and the northernmost point of the Winter Circle. In fact, Capella is the sixth brightest star in the heavens.

Completing the Circle

Then, as we start to wind down the other side of the Circle, we run into two bright stars, the twins stars in Gemini the Twins. Pollux, the brighter of the two, is our fourth corner in the Circle, and you’ll notice its “twin,” Castor, is just a bit fainter. Pollux is the sky’s 17th brightest star, and Castor is the 24th.

Our second-to-last stop around the Winter Circle is the bright star below the twins stars, Procyon. Procyon is the brightest star in Canis Minor the Lesser Dog, and in fact one of only two named stars in the constellation. For such a “minor” constellation, Procyon shines brilliantly as the seventh brightest star in the sky.

Finally, we come down to the southernmost star in the Winter Circle and the brightest of them all: Sirius in Canis Major the Greater Dog. Sirius is the brightest star in the Winter Circle and in the entire night sky. In fact, only the moon and some planets can outshine Sirius.

Finding the Winter Triangle

After you’ve found the Winter Circle, look inside it to find another asterism. That’s the Winter Triangle. First, take the last two stars of the Circle, Sirius and Procyon, then head toward the center of the Circle. That’s where you’ll find reddish star Betelgeuse, marking the shoulder of Orion. Betelgeuse makes the third corner of the Winter Triangle. Betelgeuse is the 10th brightest star in the sky and second brightest star in Orion.

Procyon, Sirius and Betelgeuse are easy to find on winter and spring evenings. Plus they form a large pattern of 3 bright stars, known as the Winter Triangle. Chart via EarthSky.

View at EarthSky Community Photos. | Cecille Kennedy of Depoe Bay, Oregon, captured this image on February 23, 2023, and wrote: “Orion appears as a beautiful giant hunter in the night sky. Orion continues to march westward and, in a few months, will disappear from the northern sky, lost in the glare of the sun. The Winter Triangle consisting of the stars Sirius, Procyon and Betelgeuse was also highly visible, as well as the Pleiades, Aldebaran of constellation Taurus and Elnath of constellation Auriga. It was a rare beautiful night for stargazing!” Thank you, Cecille!

The Circle contains areas of the Milky Way

Then for a bonus, on a dark and clear moonless night, you can see the soft-glowing river of stars that we call the Milky Way meandering right through the center of the Winter Circle.

Bottom line: The Winter Circle, aka the Winter Hexagon, is a giant shape made from some of the brightest stars in the sky, including Rigel, Aldebaran, Capella, Pollux, Procyon and Sirius. And in January 2025 Jupiter is inside the Winter Circle and Mars is nearby.

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The Winter Circle or Winter Hexagon

The Winter Circle (or Hexagon) is a large circular pattern, made of some of the brightest stars in the Northern Hemisphere’s winter sky (or the Southern Hemisphere’s summer sky). It isn’t a constellation. It’s an asterism, or prominent group of stars that form a noticeable pattern. In addition, the Winter Circle has a smaller asterism inside it, called the Winter Triangle.

Plus in 2025 the planet Jupiter lies inside the Winter Circle and Mars is nearby.

The Winter Circle (or Winter Hexagon) isn’t a constellation. It’s an asterism, made of bright stars in the winter evening sky for the Northern Hemisphere (and summer sky for the Southern Hemisphere). It covers a large portion of the sky. Chart via EarthSky.

Meet the Winter Circle

Strictly speaking, you’ll see this circular pattern of 1st-magnitude stars – the brightest stars in our sky – from six different constellations: Rigel in Orion the Hunter, Aldebaran in Taurus the Bull, Capella in Auriga the Charioteer, Pollux (and its forever companion Castor) in Gemini the Twins, Procyon in Canis Minor the Lesser Dog and Sirius in Canis Major the Greater Dog. Also, an additional 1st-magnitude star, Betelgeuse in Orion the Hunter, lies toward the center of the Circle.

The Circle is big

The Winter Circle is big! To get an idea of the it’s humongous size, the span from the southernmost star, Sirius, to the northernmost star, Capella, covers about 1/3 of the dome of the sky.

Image of the evening sky on December 31, 2024, taken with an allsky camera. The Winter Hexagon takes up a large portion of the sky. Plus in 2025, the planets Jupiter and Mars are nearby. Image via WyoAstro observatory.

2025 lunar calendars on sale now. Makes a great gift! Check it out here.

When is the Winter Circle (or Hexagon) visible?

So, like all stars, those in the Winter Circle rise and set some four minutes earlier with each passing night. Indeed, by late January, the Winter Circle will have risen high enough above the northeastern horizon so it’s visible by about 7 p.m. local time. Then, if you look around midnight, the Winter Circle will be high above the southern horizon. And later, after about 3 a.m. local time, it sinks toward the southwestern horizon, with some of it setting in the west before sunrise.

Then, in late February and early March, the Winter Circle is in your southern sky at nightfall and early evening.

View at EarthSky Community Photos. | Jose Zarcos Palma in Mina Sao Domingo, Mertola, Portugal, took this image of the Winter Circle on December 26, 2022. Jose wrote: “I planned this composition to catch the great Winter Circle in an early stage of its ascension just behind the abandoned mining ruins of Achada do Gamo. We can clearly see Sirius in the Canis Major the Greater Dog near the chimney on the right side, just below Orion the Hunter. On top of the image, the planet Mars is near Aldebaran in Taurus the Bull.” Thank you, Jose!

Finding the Winter Circle

First, to find the Winter Circle (or Hexagon), find the easily recognizable constellation of Orion the Hunter. Indeed, its three belt stars give it away. Then, look for the bright bluish star to the lower right. This star is Rigel, the southwest corner of the Winter Circle and the first of the six stars in the Circle. By the way, Rigel is the brightest star in Orion and the seventh brightest star in the night sky.

Now draw a line through Orion’s Belt stars upward to find Aldebaran, the ruddy eye of Taurus the Bull. Aldebaran is the second star in the Circle and the brightest star in Taurus. As a matter of fact, Aldebaran is the fourteenth brightest star in the sky.

Next, continue upward in a counterclockwise direction to find the next bright star, Capella in Auriga the Charioteer. Capella is the third star on our journey and the northernmost point of the Winter Circle. In fact, Capella is the sixth brightest star in the heavens.

Completing the Circle

Then, as we start to wind down the other side of the Circle, we run into two bright stars, the twins stars in Gemini the Twins. Pollux, the brighter of the two, is our fourth corner in the Circle, and you’ll notice its “twin,” Castor, is just a bit fainter. Pollux is the sky’s 17th brightest star, and Castor is the 24th.

Our second-to-last stop around the Winter Circle is the bright star below the twins stars, Procyon. Procyon is the brightest star in Canis Minor the Lesser Dog, and in fact one of only two named stars in the constellation. For such a “minor” constellation, Procyon shines brilliantly as the seventh brightest star in the sky.

Finally, we come down to the southernmost star in the Winter Circle and the brightest of them all: Sirius in Canis Major the Greater Dog. Sirius is the brightest star in the Winter Circle and in the entire night sky. In fact, only the moon and some planets can outshine Sirius.

Finding the Winter Triangle

After you’ve found the Winter Circle, look inside it to find another asterism. That’s the Winter Triangle. First, take the last two stars of the Circle, Sirius and Procyon, then head toward the center of the Circle. That’s where you’ll find reddish star Betelgeuse, marking the shoulder of Orion. Betelgeuse makes the third corner of the Winter Triangle. Betelgeuse is the 10th brightest star in the sky and second brightest star in Orion.

Procyon, Sirius and Betelgeuse are easy to find on winter and spring evenings. Plus they form a large pattern of 3 bright stars, known as the Winter Triangle. Chart via EarthSky.

View at EarthSky Community Photos. | Cecille Kennedy of Depoe Bay, Oregon, captured this image on February 23, 2023, and wrote: “Orion appears as a beautiful giant hunter in the night sky. Orion continues to march westward and, in a few months, will disappear from the northern sky, lost in the glare of the sun. The Winter Triangle consisting of the stars Sirius, Procyon and Betelgeuse was also highly visible, as well as the Pleiades, Aldebaran of constellation Taurus and Elnath of constellation Auriga. It was a rare beautiful night for stargazing!” Thank you, Cecille!

The Circle contains areas of the Milky Way

Then for a bonus, on a dark and clear moonless night, you can see the soft-glowing river of stars that we call the Milky Way meandering right through the center of the Winter Circle.

Bottom line: The Winter Circle, aka the Winter Hexagon, is a giant shape made from some of the brightest stars in the sky, including Rigel, Aldebaran, Capella, Pollux, Procyon and Sirius. And in January 2025 Jupiter is inside the Winter Circle and Mars is nearby.

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La Niña is here! Here’s what that means for our weather

La Niña is here! Read on to find out more about this weather pattern and what it means for our winter weather. Image via NOAA.

La Niña is here!

Meteorologists have been expecting it for months, and now La Niña conditions have finally emerged in the tropical Pacific Ocean. A La Niña Advisory is currently in place with a 59% chance of continuing through April 2025. According to the Climate Prediction Center, the La Niña will be weak and eventually transition into a neutral phase.

What is La Niña and El Niño?

La Niña is one phase of the climate pattern called the El Niño Southern Oscillation (ENSO), which forms in the tropical Pacific. La Niña is the “cool” phase of ENSO, since the waters in this part of the Pacific are cooler than average. El Niño is the “warm” phase of ENSO, as the waters in the tropical Pacific are warmer than average. While the focus is typically on El Niño and La Niña, there is also a neutral phase. The neutral phase of ENSO basically means everything in this part of the Pacific Ocean is at or near their averages.

During La Niña, the phase we’re in now, the trade winds over the tropical Pacific Ocean are stronger than average, which creates upwelling. Upwelling brings up cooler water from deep in the ocean, causing water temperatures to drop. Also over this part of the ocean, the air sinks, leading to less rainfall. There is rising air and therefore more rain over places like Indonesia, however.

During La Niña, air sinks over areas such as the eastern Pacific Ocean and rises over the western Pacific Ocean, such as in Indonesia. Image via NOAA.

It’s the opposite during El Niño: The winds over the tropical Pacific Ocean are weaker, and so waters stay warmer. This leads to rising motion and more active, rainy weather over this part of the ocean, while sinking air leads to calm, drier weather in other places, such as Indonesia.

El Nino leads to wetter conditions in places like the southern United States. Image via NOAA.

Walker Circulation

ENSO plays an important role in the Walker Circulation. The Walker Circulation is a cycle of rising and sinking air between the typically warmer waters of the western Pacific Ocean and the cooler waters of the eastern Pacific Ocean. It’s this Walker Circulation that helps drive the rising motion and, therefore, rain and storm activity.

What does this mean for the rest of winter?

This large circulation pattern has more of an impact on the United States in the winter, as the overall circulation can influence the location of the jet stream, a major driver for weather. So a La Niña winter for the United States (and parts of their neighbors to the north in Canada) typically features cooler weather from Alaska down to the northern Plains. It also means drier, warmer conditions from the desert southwest to the southeast. (See the map at the top of this post.)

In other parts of the world, especially for those near the western Pacific Ocean (in the Northern Hemisphere), meteorologists expect a more active, rainy trend through March.

Will La Niña impact summer and the Atlantic hurricane season?

La Niña in its current phase is not expected to last into the summer. The Climate Prediction Center anticipates the ENSO phase to become neutral sometime between March and May.

If La Niña were to remain in place for the upcoming Atlantic hurricane season, it would have had an influence on how active it could be. La Niña supports rising motion in the tropical Atlantic. And that would allow any forming tropical system to develop quickly. (Also, wind shear – the strong upper-level winds – are lower in the tropical Atlantic during La Niña. Wind shear can weaken or tear apart tropical systems, so lower wind shear would also allow for more easy tropical development.)

If La Niña were to remain in place for the upcoming Atlantic hurricane season, here’s what to expect. Image via NOAA.

The forecast and outcome

The Climate Prediction Center issued a La Niña Watch during the summer of 2024 in anticipation of the development of this ENSO phase. A La Niña Watch gets issued when a La Niña is expected to develop within the next six months. At the time, meteorologists expected La Niña would develop during the summer, impacting the already active Atlantic hurricane season. But La Niña ended up not developing until December. The National Oceanic and Atmospheric Administration speculates that because the oceans have been running well above average for more than a year, it delayed the onset of the cool phase, La Niña.

Bottom line: After being expected for months, La Niña conditions have finally emerged in the tropical Pacific Ocean. Here’s what that means for our weather.

Via NOAA and National Weather Service

The post La Niña is here! Here’s what that means for our weather first appeared on EarthSky.

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La Niña is here! Read on to find out more about this weather pattern and what it means for our winter weather. Image via NOAA.

La Niña is here!

Meteorologists have been expecting it for months, and now La Niña conditions have finally emerged in the tropical Pacific Ocean. A La Niña Advisory is currently in place with a 59% chance of continuing through April 2025. According to the Climate Prediction Center, the La Niña will be weak and eventually transition into a neutral phase.

What is La Niña and El Niño?

La Niña is one phase of the climate pattern called the El Niño Southern Oscillation (ENSO), which forms in the tropical Pacific. La Niña is the “cool” phase of ENSO, since the waters in this part of the Pacific are cooler than average. El Niño is the “warm” phase of ENSO, as the waters in the tropical Pacific are warmer than average. While the focus is typically on El Niño and La Niña, there is also a neutral phase. The neutral phase of ENSO basically means everything in this part of the Pacific Ocean is at or near their averages.

During La Niña, the phase we’re in now, the trade winds over the tropical Pacific Ocean are stronger than average, which creates upwelling. Upwelling brings up cooler water from deep in the ocean, causing water temperatures to drop. Also over this part of the ocean, the air sinks, leading to less rainfall. There is rising air and therefore more rain over places like Indonesia, however.

During La Niña, air sinks over areas such as the eastern Pacific Ocean and rises over the western Pacific Ocean, such as in Indonesia. Image via NOAA.

It’s the opposite during El Niño: The winds over the tropical Pacific Ocean are weaker, and so waters stay warmer. This leads to rising motion and more active, rainy weather over this part of the ocean, while sinking air leads to calm, drier weather in other places, such as Indonesia.

El Nino leads to wetter conditions in places like the southern United States. Image via NOAA.

Walker Circulation

ENSO plays an important role in the Walker Circulation. The Walker Circulation is a cycle of rising and sinking air between the typically warmer waters of the western Pacific Ocean and the cooler waters of the eastern Pacific Ocean. It’s this Walker Circulation that helps drive the rising motion and, therefore, rain and storm activity.

What does this mean for the rest of winter?

This large circulation pattern has more of an impact on the United States in the winter, as the overall circulation can influence the location of the jet stream, a major driver for weather. So a La Niña winter for the United States (and parts of their neighbors to the north in Canada) typically features cooler weather from Alaska down to the northern Plains. It also means drier, warmer conditions from the desert southwest to the southeast. (See the map at the top of this post.)

In other parts of the world, especially for those near the western Pacific Ocean (in the Northern Hemisphere), meteorologists expect a more active, rainy trend through March.

Will La Niña impact summer and the Atlantic hurricane season?

La Niña in its current phase is not expected to last into the summer. The Climate Prediction Center anticipates the ENSO phase to become neutral sometime between March and May.

If La Niña were to remain in place for the upcoming Atlantic hurricane season, it would have had an influence on how active it could be. La Niña supports rising motion in the tropical Atlantic. And that would allow any forming tropical system to develop quickly. (Also, wind shear – the strong upper-level winds – are lower in the tropical Atlantic during La Niña. Wind shear can weaken or tear apart tropical systems, so lower wind shear would also allow for more easy tropical development.)

If La Niña were to remain in place for the upcoming Atlantic hurricane season, here’s what to expect. Image via NOAA.

The forecast and outcome

The Climate Prediction Center issued a La Niña Watch during the summer of 2024 in anticipation of the development of this ENSO phase. A La Niña Watch gets issued when a La Niña is expected to develop within the next six months. At the time, meteorologists expected La Niña would develop during the summer, impacting the already active Atlantic hurricane season. But La Niña ended up not developing until December. The National Oceanic and Atmospheric Administration speculates that because the oceans have been running well above average for more than a year, it delayed the onset of the cool phase, La Niña.

Bottom line: After being expected for months, La Niña conditions have finally emerged in the tropical Pacific Ocean. Here’s what that means for our weather.

Via NOAA and National Weather Service

The post La Niña is here! Here’s what that means for our weather first appeared on EarthSky.

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Beloved Gaia spacecraft ending its observations

Artist’s concept of ESA’s Gaia spacecraft mapping the stars of the Milky Way. Gaia’s observations will come to an end on January 15, 2025. Image via ESA/ ATG medialab. Background ESO/ S. Brunier.

The 2025 EarthSky lunar calendar available now. Moon phases every day on a poster-sized calendar. Get yours today!

Beloved spacecraft ending its operations

Today, Wednesday, January 15, 2025, the Gaia spacecraft will take its final measurements of our Milky Way galaxy. Gaia – a mission of the European Space Agency – launched in 2013 and has been expanding our view of our home galaxy since its arrival at Lagrange Point 2 in 2014. Lagrangian points are locations in space where gravitational forces and the orbital motion of a body balance each other. The goal of Gaia was to make a precise 3D map of the Milky Way. Over the past decade, it has tracked and measured the motions, luminosity, temperature and composition of nearly 2 billion objects.

But ESA said that the cold gas propellant that keeps the mission working is running out. While Gaia will cease taking measurements of our galaxy, the data releases from the project will continue for some years yet. Gaia’s first three data releases came in 2016, 2018 and 2022. The 4th data release should be ready in 2026. And the 5th and final data release covering all 10 1/2 years of data will be around the end of the decade. The massive amounts of data take quite a long time to process!

What will happen to Gaia next?

Gaia will not float out at the Lagrange Point 2 forever. Engineers have planned to remove Gaia from its current orbit. ESA said:

Gaia will be inserted into an orbit that makes sure it does not come too close to the Earth-moon system in the near future. The Gaia spacecraft will be fully passivated when it moves to its final orbit, to avoid any harm or interference with other spacecraft.

After January 15, Gaia will undergo some testing, which will make it temporarily brighter in the sky. Normally, Gaia has been a very faint magnitude 21 as it orbits the sun out at Lagrange Point 2. But for while it will brighten to magnitude 15. That’s still incredibly faint for the casual observer. You’d need quite a large telescope to track it down. But if that’s your kind of fun, here’s information on how to find it.

What has Gaia already shown us?

Astronomers have used the data from Gaia to make all sorts of new discoveries about our galaxy. Here are some highlights:

• Gaia spotted more than 350 asteroids with possible moons
• Gaia helped discover the most massive stellar black hole in the Milky Way, named Gaia BH3
• And Gaia created an atlas of Milky Way mergers with smaller galaxies

Also, Gaia has made discoveries outside of the Milky Way, including spotting stars flying between galaxies and the discovery of an enormous ghost galaxy on the Milky Way’s outskirts.

Watch what Phil Plait had to say about Gaia during a recent livestream with Deborah Byrd.

Bottom line: ESA’s Gaia spacecraft has spent more than a decade measuring nearly 2 billion objects in our Milky Way galaxy. Its measurements end on January 15, 2025.

Via ESA

The post Beloved Gaia spacecraft ending its observations first appeared on EarthSky.

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Artist’s concept of ESA’s Gaia spacecraft mapping the stars of the Milky Way. Gaia’s observations will come to an end on January 15, 2025. Image via ESA/ ATG medialab. Background ESO/ S. Brunier.

The 2025 EarthSky lunar calendar available now. Moon phases every day on a poster-sized calendar. Get yours today!

Beloved spacecraft ending its operations

Today, Wednesday, January 15, 2025, the Gaia spacecraft will take its final measurements of our Milky Way galaxy. Gaia – a mission of the European Space Agency – launched in 2013 and has been expanding our view of our home galaxy since its arrival at Lagrange Point 2 in 2014. Lagrangian points are locations in space where gravitational forces and the orbital motion of a body balance each other. The goal of Gaia was to make a precise 3D map of the Milky Way. Over the past decade, it has tracked and measured the motions, luminosity, temperature and composition of nearly 2 billion objects.

But ESA said that the cold gas propellant that keeps the mission working is running out. While Gaia will cease taking measurements of our galaxy, the data releases from the project will continue for some years yet. Gaia’s first three data releases came in 2016, 2018 and 2022. The 4th data release should be ready in 2026. And the 5th and final data release covering all 10 1/2 years of data will be around the end of the decade. The massive amounts of data take quite a long time to process!

What will happen to Gaia next?

Gaia will not float out at the Lagrange Point 2 forever. Engineers have planned to remove Gaia from its current orbit. ESA said:

Gaia will be inserted into an orbit that makes sure it does not come too close to the Earth-moon system in the near future. The Gaia spacecraft will be fully passivated when it moves to its final orbit, to avoid any harm or interference with other spacecraft.

After January 15, Gaia will undergo some testing, which will make it temporarily brighter in the sky. Normally, Gaia has been a very faint magnitude 21 as it orbits the sun out at Lagrange Point 2. But for while it will brighten to magnitude 15. That’s still incredibly faint for the casual observer. You’d need quite a large telescope to track it down. But if that’s your kind of fun, here’s information on how to find it.

What has Gaia already shown us?

Astronomers have used the data from Gaia to make all sorts of new discoveries about our galaxy. Here are some highlights:

• Gaia spotted more than 350 asteroids with possible moons
• Gaia helped discover the most massive stellar black hole in the Milky Way, named Gaia BH3
• And Gaia created an atlas of Milky Way mergers with smaller galaxies

Also, Gaia has made discoveries outside of the Milky Way, including spotting stars flying between galaxies and the discovery of an enormous ghost galaxy on the Milky Way’s outskirts.

Watch what Phil Plait had to say about Gaia during a recent livestream with Deborah Byrd.

Bottom line: ESA’s Gaia spacecraft has spent more than a decade measuring nearly 2 billion objects in our Milky Way galaxy. Its measurements end on January 15, 2025.

Via ESA

The post Beloved Gaia spacecraft ending its observations first appeared on EarthSky.

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Huygens landed on Saturn’s moon Titan 20 years ago

Watch as Huygens descends through the atmosphere of Saturn’s moon Titan and lands on its surface on January 14, 2005.

Huygens landed on Saturn’s moon Titan 20 years ago

Right now, space probes are speeding toward the moons in the outer solar system, ready to explore these icy ocean worlds. JUICE is headed toward Jupiter’s icy moons, while Europa Clipper is zeroing in on one of Jupiter’s moons, Europa, where there’s already scientific evidence for the ingredients of life. But did you know we’ve already landed on a moon of a gas giant? On January 14, 2005, ESA’s Huygens spacecraft descended through the atmosphere of Saturn’s moon Titan, to what astronomers thought might be a wet world, but in reality it looked a bit like … Mars?

Huygens made the trip to Saturn aboard NASA’s Cassini spacecraft. After Huygens patiently waited its turn aboard Cassini for seven years, Cassini released Huygens on its trip toward Titan on December 25, 2004. On January 14, Huygens entered the moon’s atmosphere and took two hours to reach the surface. And on the surface it continued to record and send information for about 90 minutes.

The 2025 EarthSky Lunar Calendar is now available! A unique and beautiful poster-sized calendar. Get yours today!

The descent and landing

Here’s NASA’s description of the event:

Huygens entered Titan’s atmosphere at 09:05:56 UTC on January 14, 2005, and within four minutes had deployed its 28-foot (8.5-meter) diameter main parachute.

A minute later, Huygens began transmitting a wealth of information back to Cassini for more than two hours before impacting on the surface of Titan at 11:38:11 UTC at a velocity of 15 feet per second (4.54 meters per second). Landing coordinates were 192.32 degrees west longitude and 10.25 degrees south latitude, about 4 miles (7 kilometers) from its target point.

A problem in the communications program limited the number of images that Huygens transmitted to Cassini, from about 700 to 376. Yet, to the excitement of planetary scientists back on Earth, it continued its transmissions for another three hours and 10 minutes. During this time it transmitted a view of its surroundings (224 images of the same view).

Huygens appears to have landed on a surface resembling sand made of ice grains. Surface pictures showed a flat plain littered with pebbles as well as evidence of liquid acting on the terrain in the recent past. Subsequent data confirmed the existence of liquid hydrocarbon lakes in the polar regions of Titan.

Huygens images of Titan’s surface

Check out these views from Huygens as the spacecraft descended through Titan’s hazy atmosphere and then made out the varied terrain below.

Here are 6 fisheye views that Huygens captured on its descent through Titan’s atmosphere and to the surface. Image via ESA/ NASA/ JPL/ University of Arizona.

Here’s another collection of 4 images from Huygens on January 14, 2005. The spacecraft broke out of the haze in Titan’s atmosphere and got a view of the rugged terrain below. Image via ESA/ NASA/ JPL/ University of Arizona.

And here was the view from Titan’s surface.

Huygens captured this view of Titan’s surface on January 14, 2005. It shows pebble-sized rocks or ice blocks. Image via ESA/ NASA/ JPL/ University of Arizona.

Next up, Europa Clipper and JUICE

How different – or similar – will our views of Jupiter’s moons be? Europa Clipper will arrive at Europa in 2030 and JUICE will reach the Jovian moons in 2031. The Europa Clipper mission will only perform flybys of Europa, no landing. But, interestingly, both Europa Clipper and JUICE will end their missions by deliberately crashing into Ganymede. ESA said:

… there is the possibility that – depending on the missions’ end dates – one spacecraft might have the chance to observe the effects of the other’s impact.

Bottom line: On January 14, 2005, the Huygens spacecraft descended through the atmosphere of Saturn’s moon Titan and landed on its surface. See the 20th anniversary images of Titan here.

The post Huygens landed on Saturn’s moon Titan 20 years ago first appeared on EarthSky.

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Watch as Huygens descends through the atmosphere of Saturn’s moon Titan and lands on its surface on January 14, 2005.

Huygens landed on Saturn’s moon Titan 20 years ago

Right now, space probes are speeding toward the moons in the outer solar system, ready to explore these icy ocean worlds. JUICE is headed toward Jupiter’s icy moons, while Europa Clipper is zeroing in on one of Jupiter’s moons, Europa, where there’s already scientific evidence for the ingredients of life. But did you know we’ve already landed on a moon of a gas giant? On January 14, 2005, ESA’s Huygens spacecraft descended through the atmosphere of Saturn’s moon Titan, to what astronomers thought might be a wet world, but in reality it looked a bit like … Mars?

Huygens made the trip to Saturn aboard NASA’s Cassini spacecraft. After Huygens patiently waited its turn aboard Cassini for seven years, Cassini released Huygens on its trip toward Titan on December 25, 2004. On January 14, Huygens entered the moon’s atmosphere and took two hours to reach the surface. And on the surface it continued to record and send information for about 90 minutes.

The 2025 EarthSky Lunar Calendar is now available! A unique and beautiful poster-sized calendar. Get yours today!

The descent and landing

Here’s NASA’s description of the event:

Huygens entered Titan’s atmosphere at 09:05:56 UTC on January 14, 2005, and within four minutes had deployed its 28-foot (8.5-meter) diameter main parachute.

A minute later, Huygens began transmitting a wealth of information back to Cassini for more than two hours before impacting on the surface of Titan at 11:38:11 UTC at a velocity of 15 feet per second (4.54 meters per second). Landing coordinates were 192.32 degrees west longitude and 10.25 degrees south latitude, about 4 miles (7 kilometers) from its target point.

A problem in the communications program limited the number of images that Huygens transmitted to Cassini, from about 700 to 376. Yet, to the excitement of planetary scientists back on Earth, it continued its transmissions for another three hours and 10 minutes. During this time it transmitted a view of its surroundings (224 images of the same view).

Huygens appears to have landed on a surface resembling sand made of ice grains. Surface pictures showed a flat plain littered with pebbles as well as evidence of liquid acting on the terrain in the recent past. Subsequent data confirmed the existence of liquid hydrocarbon lakes in the polar regions of Titan.

Huygens images of Titan’s surface

Check out these views from Huygens as the spacecraft descended through Titan’s hazy atmosphere and then made out the varied terrain below.

Here are 6 fisheye views that Huygens captured on its descent through Titan’s atmosphere and to the surface. Image via ESA/ NASA/ JPL/ University of Arizona.

Here’s another collection of 4 images from Huygens on January 14, 2005. The spacecraft broke out of the haze in Titan’s atmosphere and got a view of the rugged terrain below. Image via ESA/ NASA/ JPL/ University of Arizona.

And here was the view from Titan’s surface.

Huygens captured this view of Titan’s surface on January 14, 2005. It shows pebble-sized rocks or ice blocks. Image via ESA/ NASA/ JPL/ University of Arizona.

Next up, Europa Clipper and JUICE

How different – or similar – will our views of Jupiter’s moons be? Europa Clipper will arrive at Europa in 2030 and JUICE will reach the Jovian moons in 2031. The Europa Clipper mission will only perform flybys of Europa, no landing. But, interestingly, both Europa Clipper and JUICE will end their missions by deliberately crashing into Ganymede. ESA said:

… there is the possibility that – depending on the missions’ end dates – one spacecraft might have the chance to observe the effects of the other’s impact.

Bottom line: On January 14, 2005, the Huygens spacecraft descended through the atmosphere of Saturn’s moon Titan and landed on its surface. See the 20th anniversary images of Titan here.

The post Huygens landed on Saturn’s moon Titan 20 years ago first appeared on EarthSky.

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