View at EarthSky Community Photos. | Jeremy Likness in Prineville, Oregon, captured the Milky Way on April 18, 2026. Jeremy wrote: “It dropped into the 30s the night I photographed this. I had a sleeping bag and a small 1-person tent to sleep in. I enjoyed the experience, but it’s scenes like these that make it all worth it. This may be my new favorite Milky Way.” Thank you, Jeremy! See more pics from the start of Milky Way season below.
Milky Way season is back!
The Milky Way is a cloudy stretch of stars and dust that make up our home galaxy. In Northern Hemisphere spring, the starry stretch of our galaxy begins to rise above the horizon in the early morning hours. So, if you’re up before the sun at this time of year, you may see the Milky Way returning to dark skies.
Many of our global members of the EarthSky community have been up early to capture the Milky Way. Enjoy their wonderful photos here. Do you have one of your own to share? Submit it to us!
View at EarthSky Community Photos. | Melissa Neadle at Assateague Island National Seashore in Maryland caught the Milky Way on April 18, 2026. Melissa wrote: “This panorama of the Milky Way taken on one of the marsh trails shows the wide range of sky darkness levels in a single location. On the right side you’re facing the beautiful dark skies over the Atlantic Ocean. You can see the details of the core and some lovely green and magenta sky glow. But on the left you are looking toward Ocean City, Maryland. The resulting light pollution washes out the sky completely at the horizon.” Thank you, Melissa!View at EarthSky Community Photos. | Randy Strauss in southeastern Nebraska captured the Milky Way galaxy on April 14, 2026. Randy wrote: “My first view of the Milky Way in 2026. This time of year it rises in the east around 2 a.m. and remains relatively low to the horizon until sunrise.” Thank you, Randy!View at EarthSky Community Photos. | Abhishek Konale in Jaisalmer, India, captured the Milky Way on March 21, 2026. Abhishek wrote: “The Milky Way core rising with the mystical hues of the Rho Ophiuchi complex, quietly revealing itself between passing clouds. The clouds ended up adding a special touch, acting like a natural star glow filter. And I was honestly really impressed with how the final image turned out. This 2-day desert camping journey into Desert National Park, Jaisalmer, wasn’t just about the stars. It was about the ride across endless dunes on camelback, unexpected desert rains, meals cooked over a wooden fire and long conversations under uncertain skies.” Thank you, Abhishek!
More images of our home galaxy
View at EarthSky Community Photos. | Jelieta Walinski at Montezuma Pass, Coronado National Memorial, Arizona, captured this shot on March 19, 2026. Jelieta wrote: “The Milky Way is a barred spiral system containing over 100 billion stars, its glowing core rich with interstellar dust, hydrogen clouds and stellar nurseries. That soft, radiant arc is not merely light, it is structure: the dense galactic plane seen edge-on from our position within it.” Thank you, Jelieta!View at EarthSky Community Photos. | Meiying Lee in Mount Cook National Park, New Zealand, captured the Milky Way on March 19, 2026. Meiying wrote: “The southern Milky Way rises directly from the horizon, shining with remarkable clarity. On the right side of the sky, 2 faint, cloud-like patches stand out. These are the Large and Small Magellanic Clouds, iconic features of the Southern Hemisphere. Near the horizon, subtle hues of green and red glow softly. This is airglow, quietly revealing just how pure and transparent the sky is here.” Thank you, Meiying!View at EarthSky Community Photos. | Aayan Shaikh in Sindhudurg, Maharashtra, India, captured the Milky Way on March 13, 2026. Aayan wrote: “Got a truly clear night sky and shot this wonderful creation of our universe.” Thank you, Aayan!
Milky Way season at Joshua Tree
View at EarthSky Community Photos. | Enji Chung captured this Milky Way image on April 18, 2026. Enji wrote: “I finally got a chance to get outside and shoot the Milky Way during International Dark Sky Week. I took this image in Joshua Tree National Park. The green-yellow glow is from Palm Springs.” Thank you, Enji!
Bottom line: Enjoy the beauty of our home galaxy in these images from the start of the Milky Way season. Thanks to our talented astrophotographers in the EarthSky community!
View at EarthSky Community Photos. | Jeremy Likness in Prineville, Oregon, captured the Milky Way on April 18, 2026. Jeremy wrote: “It dropped into the 30s the night I photographed this. I had a sleeping bag and a small 1-person tent to sleep in. I enjoyed the experience, but it’s scenes like these that make it all worth it. This may be my new favorite Milky Way.” Thank you, Jeremy! See more pics from the start of Milky Way season below.
Milky Way season is back!
The Milky Way is a cloudy stretch of stars and dust that make up our home galaxy. In Northern Hemisphere spring, the starry stretch of our galaxy begins to rise above the horizon in the early morning hours. So, if you’re up before the sun at this time of year, you may see the Milky Way returning to dark skies.
Many of our global members of the EarthSky community have been up early to capture the Milky Way. Enjoy their wonderful photos here. Do you have one of your own to share? Submit it to us!
View at EarthSky Community Photos. | Melissa Neadle at Assateague Island National Seashore in Maryland caught the Milky Way on April 18, 2026. Melissa wrote: “This panorama of the Milky Way taken on one of the marsh trails shows the wide range of sky darkness levels in a single location. On the right side you’re facing the beautiful dark skies over the Atlantic Ocean. You can see the details of the core and some lovely green and magenta sky glow. But on the left you are looking toward Ocean City, Maryland. The resulting light pollution washes out the sky completely at the horizon.” Thank you, Melissa!View at EarthSky Community Photos. | Randy Strauss in southeastern Nebraska captured the Milky Way galaxy on April 14, 2026. Randy wrote: “My first view of the Milky Way in 2026. This time of year it rises in the east around 2 a.m. and remains relatively low to the horizon until sunrise.” Thank you, Randy!View at EarthSky Community Photos. | Abhishek Konale in Jaisalmer, India, captured the Milky Way on March 21, 2026. Abhishek wrote: “The Milky Way core rising with the mystical hues of the Rho Ophiuchi complex, quietly revealing itself between passing clouds. The clouds ended up adding a special touch, acting like a natural star glow filter. And I was honestly really impressed with how the final image turned out. This 2-day desert camping journey into Desert National Park, Jaisalmer, wasn’t just about the stars. It was about the ride across endless dunes on camelback, unexpected desert rains, meals cooked over a wooden fire and long conversations under uncertain skies.” Thank you, Abhishek!
More images of our home galaxy
View at EarthSky Community Photos. | Jelieta Walinski at Montezuma Pass, Coronado National Memorial, Arizona, captured this shot on March 19, 2026. Jelieta wrote: “The Milky Way is a barred spiral system containing over 100 billion stars, its glowing core rich with interstellar dust, hydrogen clouds and stellar nurseries. That soft, radiant arc is not merely light, it is structure: the dense galactic plane seen edge-on from our position within it.” Thank you, Jelieta!View at EarthSky Community Photos. | Meiying Lee in Mount Cook National Park, New Zealand, captured the Milky Way on March 19, 2026. Meiying wrote: “The southern Milky Way rises directly from the horizon, shining with remarkable clarity. On the right side of the sky, 2 faint, cloud-like patches stand out. These are the Large and Small Magellanic Clouds, iconic features of the Southern Hemisphere. Near the horizon, subtle hues of green and red glow softly. This is airglow, quietly revealing just how pure and transparent the sky is here.” Thank you, Meiying!View at EarthSky Community Photos. | Aayan Shaikh in Sindhudurg, Maharashtra, India, captured the Milky Way on March 13, 2026. Aayan wrote: “Got a truly clear night sky and shot this wonderful creation of our universe.” Thank you, Aayan!
Milky Way season at Joshua Tree
View at EarthSky Community Photos. | Enji Chung captured this Milky Way image on April 18, 2026. Enji wrote: “I finally got a chance to get outside and shoot the Milky Way during International Dark Sky Week. I took this image in Joshua Tree National Park. The green-yellow glow is from Palm Springs.” Thank you, Enji!
Bottom line: Enjoy the beauty of our home galaxy in these images from the start of the Milky Way season. Thanks to our talented astrophotographers in the EarthSky community!
You’ll see Leo the Lion in the sky in 2 parts. First, the stars making up a backward question mark represent Leo’s head. That part is known as the Sickle. Second, the triangle at the back represents the Lion’s hindquarters. Also, the bright star Regulus is the bright dot at the bottom of the backward question mark. Chart via EarthSky.
Leo the Lion is one of the easiest of the 13 constellations of the zodiac to see. First, you can start by finding the bright star Regulus. And then trace out a distinctive pattern of stars shaped like a backward question mark, known as the Sickle.
From a Northern Hemisphere perspective, the Lion is a fair-weather friend, springing into the early evening sky around the March equinox. While, from the Southern Hemisphere, it’s a familiar constellation in the fall.
In fact, April and May are superb months for identifying Leo the Lion. That’s because this constellation becomes visible as soon as darkness falls and stays out until the wee hours of the morning. Remember, you are looking for a backward question mark pattern. Note that Leo’s brightest star, Regulus, is a sparkling blue-white beauty of a star, located at the bottom of the backward question mark. So, Regulus depicts the Lion’s Heart.
The constellation Leo the Lion
Even though the Sickle is the most obvious pattern in Leo, there’s another distinctive shape in Leo. That’s the triangle of stars in eastern Leo representing the Lion’s hindquarters and tail. The name of the brightest star of that triangle is Denebola, which stems from an Arabic term meaning the Lion’s Tail.
Like all stars, Leo’s stars return to the same place in the sky some four minutes earlier daily or two hours earlier monthly. In early April, the constellation Leo reaches its high point for the night around 10 p.m. your local time (11 p.m. local daylight saving time), and starts to sink below the western horizon around 4 a.m. local time (5 a.m. local daylight saving time).
By around May 1, Leo reaches its high point for the night around 8 p.m. local time (9 p.m. local daylight saving time). Also, in early May, the mighty Lion begins to set in the west around 2 a.m. local time (3 a.m. daylight saving time). By June, you’ll find Leo descending in the west in the evening.
Though Leo drifts progressively westward in the early evening sky as the months go by, you can see the Lion in the evening till July. But by late July or early August, the Lion begins to fade into the sunset. And then, from about August 10 to September 16, the sun passes in front of Leo. The constellation returns to the eastern predawn sky in late September or October.
Find Leo by star-hopping from the Big Dipper
If you’re familiar with the Big Dipper star pattern – or asterism – you can star-hop to Leo the Lion every time. After the March equinox, the Big Dipper stands pretty much on its handle in the northeastern sky at nightfall. So at nightfall in April, look for the Big Dipper high in the northeast sky.
And at nightfall in May, look for the almost upside-down Big Dipper high in the north, above Polaris, the North Star. Then, identify the two pointer stars of the Big Dipper. Those are the two outer stars in the Big Dipper’s bowl. Now, draw an imaginary line southward toward the stars in Leo.
An imaginary line drawn southward from the pointer stars in the Big Dipper – the two outer stars in the Dipper’s bowl – points toward Leo the Lion. Chart via EarthSky.
What can you see with a telescope in the Lion?
Check out the chart below to get a sense of the telescopic riches that lie within the boundaries of this constellation.
The star Algieba or γ Leonis is a double star, visible in a small telescope when the atmosphere is steady. If the stars are twinkling wildly, that indicates a turbulent – not steady – atmosphere. On the other hand, if the stars are twinkling very little or not at all, try your luck at splitting Algieba – which looks like a single star to the eye – into its two colorful component stars with the telescope. By the way, you may notice one star appears orangish and the other one appears greenish-yellow.
Also, a pair of galaxies in Leo provides an inviting target for most telescopes. They are M95 and M96. What’s more, with a low-powered telescope, you might be able to fit both M95 and M96, along with M105, into a single field of view.
Next, try your luck with another galaxy trio. First, look for M65 and M66. Finally, look for NGC 3628. These three galaxies are known as the Leo Triplet galaxy group.
Notably, Leo the Lion is associated with the sun and has been for epochs. The ancient Egyptians held Leo in the highest esteem. That’s because the sun shone in front of Leo at the time of the annual flooding of the Nile River, the lifeblood of this agricultural nation.
So maybe the various lion-headed fountains designed by Greek and Roman architects symbolize the life-giving waters being released by the sun’s presence in Leo.
Also, in astrology, the sun rules Leo, one of the three fire signs of the zodiac.
In fact, many stories feature Leo the Lion. Perhaps the two better-known tales feature Heracles’ (also known as Hercules) first labor with the notorious Nemean Lion, and the Roman author Ovid’s rendering of the tragic love affair of Pyramus and Thisbe.
Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations that was published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons.Leo the Lion, from an ancient manuscript dating sometime between 1001 and 1100 CE. Image via National Library of Wales/ Wikimedia Commons (CC0 1.0).
Galaxies in Leo from Earthsky Community Photos
View at EarthSky Community Photos. | Steven Bellavia in Scottsburg, Virginia, captured these exposures of the Leo Triplet of galaxies on March 19, 2026. Steven wrote: “I have always enjoyed images of the Leo Triplet of galaxies. But I have also always wanted to capture them close up, one at a time, as each one is beautiful and full of intricate colors and details, often missed in the wide-field images. So on my recent astro-camping trip to the Staunton River Star Party, I captured 2 of the 3, close up, with the 3rd from a year ago, also from the same star party.” Thank you, Steven!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured a bunch of galaxies in the constellation Leo, including Messier 95, Messier 96 and Messier 105, on February 4, 2025. Andy wrote: “These 3 Messier objects are located right under Leo’s tummy. If all goes well in a day or two I will also post a pic of Leo’s Triplet [see above]. Leo seems to be the beginning of the constellation season. So here we go.” Thank you, Andy!
Bottom line: Leo the Lion – one of the zodiacal constellations – is a prominent fixture in the evening sky from April through June. What’s more, it’s quite easy to spot.
You’ll see Leo the Lion in the sky in 2 parts. First, the stars making up a backward question mark represent Leo’s head. That part is known as the Sickle. Second, the triangle at the back represents the Lion’s hindquarters. Also, the bright star Regulus is the bright dot at the bottom of the backward question mark. Chart via EarthSky.
Leo the Lion is one of the easiest of the 13 constellations of the zodiac to see. First, you can start by finding the bright star Regulus. And then trace out a distinctive pattern of stars shaped like a backward question mark, known as the Sickle.
From a Northern Hemisphere perspective, the Lion is a fair-weather friend, springing into the early evening sky around the March equinox. While, from the Southern Hemisphere, it’s a familiar constellation in the fall.
In fact, April and May are superb months for identifying Leo the Lion. That’s because this constellation becomes visible as soon as darkness falls and stays out until the wee hours of the morning. Remember, you are looking for a backward question mark pattern. Note that Leo’s brightest star, Regulus, is a sparkling blue-white beauty of a star, located at the bottom of the backward question mark. So, Regulus depicts the Lion’s Heart.
The constellation Leo the Lion
Even though the Sickle is the most obvious pattern in Leo, there’s another distinctive shape in Leo. That’s the triangle of stars in eastern Leo representing the Lion’s hindquarters and tail. The name of the brightest star of that triangle is Denebola, which stems from an Arabic term meaning the Lion’s Tail.
Like all stars, Leo’s stars return to the same place in the sky some four minutes earlier daily or two hours earlier monthly. In early April, the constellation Leo reaches its high point for the night around 10 p.m. your local time (11 p.m. local daylight saving time), and starts to sink below the western horizon around 4 a.m. local time (5 a.m. local daylight saving time).
By around May 1, Leo reaches its high point for the night around 8 p.m. local time (9 p.m. local daylight saving time). Also, in early May, the mighty Lion begins to set in the west around 2 a.m. local time (3 a.m. daylight saving time). By June, you’ll find Leo descending in the west in the evening.
Though Leo drifts progressively westward in the early evening sky as the months go by, you can see the Lion in the evening till July. But by late July or early August, the Lion begins to fade into the sunset. And then, from about August 10 to September 16, the sun passes in front of Leo. The constellation returns to the eastern predawn sky in late September or October.
Find Leo by star-hopping from the Big Dipper
If you’re familiar with the Big Dipper star pattern – or asterism – you can star-hop to Leo the Lion every time. After the March equinox, the Big Dipper stands pretty much on its handle in the northeastern sky at nightfall. So at nightfall in April, look for the Big Dipper high in the northeast sky.
And at nightfall in May, look for the almost upside-down Big Dipper high in the north, above Polaris, the North Star. Then, identify the two pointer stars of the Big Dipper. Those are the two outer stars in the Big Dipper’s bowl. Now, draw an imaginary line southward toward the stars in Leo.
An imaginary line drawn southward from the pointer stars in the Big Dipper – the two outer stars in the Dipper’s bowl – points toward Leo the Lion. Chart via EarthSky.
What can you see with a telescope in the Lion?
Check out the chart below to get a sense of the telescopic riches that lie within the boundaries of this constellation.
The star Algieba or γ Leonis is a double star, visible in a small telescope when the atmosphere is steady. If the stars are twinkling wildly, that indicates a turbulent – not steady – atmosphere. On the other hand, if the stars are twinkling very little or not at all, try your luck at splitting Algieba – which looks like a single star to the eye – into its two colorful component stars with the telescope. By the way, you may notice one star appears orangish and the other one appears greenish-yellow.
Also, a pair of galaxies in Leo provides an inviting target for most telescopes. They are M95 and M96. What’s more, with a low-powered telescope, you might be able to fit both M95 and M96, along with M105, into a single field of view.
Next, try your luck with another galaxy trio. First, look for M65 and M66. Finally, look for NGC 3628. These three galaxies are known as the Leo Triplet galaxy group.
Notably, Leo the Lion is associated with the sun and has been for epochs. The ancient Egyptians held Leo in the highest esteem. That’s because the sun shone in front of Leo at the time of the annual flooding of the Nile River, the lifeblood of this agricultural nation.
So maybe the various lion-headed fountains designed by Greek and Roman architects symbolize the life-giving waters being released by the sun’s presence in Leo.
Also, in astrology, the sun rules Leo, one of the three fire signs of the zodiac.
In fact, many stories feature Leo the Lion. Perhaps the two better-known tales feature Heracles’ (also known as Hercules) first labor with the notorious Nemean Lion, and the Roman author Ovid’s rendering of the tragic love affair of Pyramus and Thisbe.
Leo the Lion, with the constellation Leo Minor, as it appears in Urania’s Mirror, a set of cards by Sidney Hall depicting the constellations that was published in 1825. Image via U.S. Library of Congress/ Wikimedia Commons.Leo the Lion, from an ancient manuscript dating sometime between 1001 and 1100 CE. Image via National Library of Wales/ Wikimedia Commons (CC0 1.0).
Galaxies in Leo from Earthsky Community Photos
View at EarthSky Community Photos. | Steven Bellavia in Scottsburg, Virginia, captured these exposures of the Leo Triplet of galaxies on March 19, 2026. Steven wrote: “I have always enjoyed images of the Leo Triplet of galaxies. But I have also always wanted to capture them close up, one at a time, as each one is beautiful and full of intricate colors and details, often missed in the wide-field images. So on my recent astro-camping trip to the Staunton River Star Party, I captured 2 of the 3, close up, with the 3rd from a year ago, also from the same star party.” Thank you, Steven!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured a bunch of galaxies in the constellation Leo, including Messier 95, Messier 96 and Messier 105, on February 4, 2025. Andy wrote: “These 3 Messier objects are located right under Leo’s tummy. If all goes well in a day or two I will also post a pic of Leo’s Triplet [see above]. Leo seems to be the beginning of the constellation season. So here we go.” Thank you, Andy!
Bottom line: Leo the Lion – one of the zodiacal constellations – is a prominent fixture in the evening sky from April through June. What’s more, it’s quite easy to spot.
NASA celebrates Hubble’s 36th anniversary with a new image of the Trifid Nebula, a star-forming region it first captured in 1997. Watch a video below to see how the nebula has changed over in time. Image via NASA/ ESA/ STScI. Image Processing: Joseph DePasquale (STScI)
The Hubble Space Telescope is celebrating its 36th anniversary. The telescope launched to space on April 24, 1990.
To celebrate, NASA released a new image of the Trifid Nebula. The Trifid Nebula is a star-forming region in the Milky Way in the direction of Sagittarius.
The Trifid Nebula has changed since Hubble first imaged it. See the changes to the nebula in a video here.
The Trifid Nebula highlights Hubble’s 36 anniversary
Today, April 24, marks the 36th anniversary of the Hubble Space Telescope‘s launch! For the anniversary, Hubble captured this shimmering region of star-formation – a close-up of the Trifid Nebula about 5,000 light-years from Earth – in intricate detail. The colors in this visible light image are reminiscent of an underwater scene filled with fine-grained sediments fluttering through the ocean’s depths.
Several massive stars, which are outside this field of view, have shaped this region for at least 300,000 years. Their powerful winds continue to blow an enormous bubble. And a small portion of that bubble is showcased in the image here. The winds push and compress the cloud’s gas and dust, triggering new waves of star formation.
This isn’t the first time Hubble has gazed at this scene. The telescope observed the Trifid in 1997. And now, 29 years later, it has leveraged almost its full operational lifetime to show us changes in the nebula on human time scales. Why look at the same location again? In addition to seeing changes over time, Hubble is also equipped with an improved camera with a wider field of view and greater sensitivity that was installed during Servicing Mission 4 in 2009.
See the nebula change over time
Watch this video to see the Trifid Nebula change over time.
Bottom line: It’s the Hubble Space Telescope’s 36th anniversary! To celebrate, NASA has released an image of the iconic Trifid Nebula.
NASA celebrates Hubble’s 36th anniversary with a new image of the Trifid Nebula, a star-forming region it first captured in 1997. Watch a video below to see how the nebula has changed over in time. Image via NASA/ ESA/ STScI. Image Processing: Joseph DePasquale (STScI)
The Hubble Space Telescope is celebrating its 36th anniversary. The telescope launched to space on April 24, 1990.
To celebrate, NASA released a new image of the Trifid Nebula. The Trifid Nebula is a star-forming region in the Milky Way in the direction of Sagittarius.
The Trifid Nebula has changed since Hubble first imaged it. See the changes to the nebula in a video here.
The Trifid Nebula highlights Hubble’s 36 anniversary
Today, April 24, marks the 36th anniversary of the Hubble Space Telescope‘s launch! For the anniversary, Hubble captured this shimmering region of star-formation – a close-up of the Trifid Nebula about 5,000 light-years from Earth – in intricate detail. The colors in this visible light image are reminiscent of an underwater scene filled with fine-grained sediments fluttering through the ocean’s depths.
Several massive stars, which are outside this field of view, have shaped this region for at least 300,000 years. Their powerful winds continue to blow an enormous bubble. And a small portion of that bubble is showcased in the image here. The winds push and compress the cloud’s gas and dust, triggering new waves of star formation.
This isn’t the first time Hubble has gazed at this scene. The telescope observed the Trifid in 1997. And now, 29 years later, it has leveraged almost its full operational lifetime to show us changes in the nebula on human time scales. Why look at the same location again? In addition to seeing changes over time, Hubble is also equipped with an improved camera with a wider field of view and greater sensitivity that was installed during Servicing Mission 4 in 2009.
See the nebula change over time
Watch this video to see the Trifid Nebula change over time.
Bottom line: It’s the Hubble Space Telescope’s 36th anniversary! To celebrate, NASA has released an image of the iconic Trifid Nebula.
The LA County Natural History Museum’s 2026 City Nature Challenge runs now through Monday, April 27, 2026. The goal is to collect images of wildlife in local neighborhoods around the world. To join in, visit the 2026 City Nature Challenge page. Image via fauxels/ Pexels.
This is your global invitation to go exploring at home
The LA County Natural History Museum wants the entire world to go outside and have a good look around this weekend. They’d like us all to take a close gander at the biosphere in our neighborhoods. And they want us record what we find from now through Monday, April 27, 2026.
This annual event isn’t just a great opportunity to experience wildlife at home. Indeed, it’s also a chance to provide critical scientific data about our ever-changing biosphere. From the City Nature Challenge website:
The City Nature Challenge is an international effort to document nature in cities. The global event calls on current and aspiring community scientists, nature and science fans, and people of all ages and backgrounds to get outside and observe and submit pictures of wild plants, animals, and fungi during the Challenge dates in order to help scientists track real-time changes in our planet’s biodiversity and better understand wildlife conservation.
Wildlife only, please!
We’re sure your lawn and landscaping are no doubt lovely. But this event is about observing and recording the wild things that call the world immediately around you their home.
So here’s what the folks at the museum would like to know:
What can you find in your house?
What can you see through your windows?
And what are the wild plants growing in your backyard? (Weeds count!)
What insects or other creatures are using the cultivated plants in your backyard as a habitat or a food source?
What observations can you make along the sidewalk in front of your house or apartment complex? (Always be mindful of traffic and safety.)
Even though you don’t even have to go outside to participate, the museum suggests going for a walk. Or venture into the weeds and visit your local park. And remember to look up in the trees, underneath everything. That means getting low to see what’s creeping and crawling down there.
Pics or it didn’t happen!
Of course, recording your adventures in pictures and sharing them is the most important part of the challenge. Thankfully, iNaturalist.org makes that really simple.
Here’s how to join in from the challenge website:
Step 1: Find wildlife anywhere in LA County. (Or your local area).
Step 2: Take photos of WILD** plants and animals.
Step 3: Share your observations in the iNaturalist app. If it’s planted or taken care of by people it is not WILD. Mark it captive/cultivated!
Step 4: Learn more as your finds get identified.
**Wild means not captive or cultivated. Try not to take pictures of captive animals in zoos or aquaria and cultivated plants in your garden or at a nursery.
By the way, we’d love to see and share your images of nature too. Check out EarthSky Community Photos to find out more.
Bottom line: This weekend, April 24-27, 2026, join the global City Nature Challenge and record the biosphere in your neighborhood to help track real-time change.
The LA County Natural History Museum’s 2026 City Nature Challenge runs now through Monday, April 27, 2026. The goal is to collect images of wildlife in local neighborhoods around the world. To join in, visit the 2026 City Nature Challenge page. Image via fauxels/ Pexels.
This is your global invitation to go exploring at home
The LA County Natural History Museum wants the entire world to go outside and have a good look around this weekend. They’d like us all to take a close gander at the biosphere in our neighborhoods. And they want us record what we find from now through Monday, April 27, 2026.
This annual event isn’t just a great opportunity to experience wildlife at home. Indeed, it’s also a chance to provide critical scientific data about our ever-changing biosphere. From the City Nature Challenge website:
The City Nature Challenge is an international effort to document nature in cities. The global event calls on current and aspiring community scientists, nature and science fans, and people of all ages and backgrounds to get outside and observe and submit pictures of wild plants, animals, and fungi during the Challenge dates in order to help scientists track real-time changes in our planet’s biodiversity and better understand wildlife conservation.
Wildlife only, please!
We’re sure your lawn and landscaping are no doubt lovely. But this event is about observing and recording the wild things that call the world immediately around you their home.
So here’s what the folks at the museum would like to know:
What can you find in your house?
What can you see through your windows?
And what are the wild plants growing in your backyard? (Weeds count!)
What insects or other creatures are using the cultivated plants in your backyard as a habitat or a food source?
What observations can you make along the sidewalk in front of your house or apartment complex? (Always be mindful of traffic and safety.)
Even though you don’t even have to go outside to participate, the museum suggests going for a walk. Or venture into the weeds and visit your local park. And remember to look up in the trees, underneath everything. That means getting low to see what’s creeping and crawling down there.
Pics or it didn’t happen!
Of course, recording your adventures in pictures and sharing them is the most important part of the challenge. Thankfully, iNaturalist.org makes that really simple.
Here’s how to join in from the challenge website:
Step 1: Find wildlife anywhere in LA County. (Or your local area).
Step 2: Take photos of WILD** plants and animals.
Step 3: Share your observations in the iNaturalist app. If it’s planted or taken care of by people it is not WILD. Mark it captive/cultivated!
Step 4: Learn more as your finds get identified.
**Wild means not captive or cultivated. Try not to take pictures of captive animals in zoos or aquaria and cultivated plants in your garden or at a nursery.
By the way, we’d love to see and share your images of nature too. Check out EarthSky Community Photos to find out more.
Bottom line: This weekend, April 24-27, 2026, join the global City Nature Challenge and record the biosphere in your neighborhood to help track real-time change.
Figure A shows a dark matter map in our neighborhood of the universe. The 2 blobs are dark matter halos of the Milky Way and Andromeda galaxies. Figure B zooms in to show a small dark matter clump about 700 million years after the Big Bang. Then C-1 and C-2 are stars and gas in the simulated ultra-faint dwarf galaxy. These show different radiation levels shortly after the Big Bang. Ultra-faint dwarf galaxies change their properties depending on which radiation is used. The scale on each image is in units of light-years. Image via Royal Astronomical Society/ J Sureda/ A Fattahi/ S Brown/ S Avraham. Attribution (CC BY 4.0).
Ultra-faint dwarf galaxies – tiny satellites of the Milky Way – act as cosmic fossils. They preserve clues about radiation and star formation in the early universe.
New high-resolution simulations show these faint galaxies are extremely sensitive to early-universe conditions. Those conditions determined whether small dark matter halos formed stars or stayed dark.
Future observations from the Vera C. Rubin Observatory could use these galaxies to reconstruct the universe’s earliest climate.
Ultra-faint dwarf galaxies show state of the early universe
Ultra-faint dwarf galaxies – tiny satellite galaxies orbiting the Milky Way – have long been seen as cosmic fossils.
Now, a new study published April 24, 2026, in Monthly Notices of the Royal Astronomical Society uses an unprecedented set of simulations to show just how powerfully these faint systems can reflect the conditions of the early universe. And it tells us why some galaxies grew and others did not.
These little galaxies could also reveal what the universe’s earliest ‘climate’ was like. For example, it could show the level of radiation and how this impacted whether and where stars formed.
Astronomers often describe dwarf galaxies as small cousins of the Milky Way. They form in small dark matter halos predicted by the standard model of cosmology. The faintest examples of such systems are extreme in both size and fragility. And they lie on the boundary of our knowledge about galaxy formation and dark matter.
Simulating tiny galaxies
Associate professor Azadeh Fattahi, of the Oskar Klein Centre (OKC) in Stockholm, led the new study with the LYRA collaboration and in collaboration with Durham University and the University of Hawaii. Fattahi said:
In this work we presented a brand-new suite of cosmological simulations focused on the faintest galaxies in the universe, with an unprecedented resolution. These are by far the largest sample of such galaxies ever simulated at these resolutions. The smallest galaxies are called ultra-faint dwarf galaxies, which are a million times less massive than the Milky Way or even smaller. Due to their small size these galaxies have proven very difficult to model and simulate.
This new simulation suite represents a major step forward, enabling a systematic view of how these galaxies form and evolve.
A down-to-earth analogy
Shaun Brown led the study while working at OKC and Durham University. Brown said:
A useful analogy is to plants and crops and how they grow is sensitive to the weather conditions. In the same way that the yield of a crop in summer can indirectly tell you a lot about what the weather in spring must have been like, the properties of faint dwarf galaxies today can tell us a lot about the conditions, or weather, of the universe at a much earlier time.
What makes the results especially timely is that the simulations do more than reproduce faint dwarf galaxies. They suggest that these local objects can act as a probe of the universe’s earliest ‘climate’. The team explored how different assumptions about the early radiation environment influence which small dark matter haloes manage to form stars at all. Brown explained:
In the paper we studied two different assumptions about the properties of the early universe when it was less than 500 million years old, to understand the effect on the properties of these small galaxies today when the universe is 13 billion years old. We found that these small ultra-faint galaxies are very sensitive to these changes, while more massive galaxies, like our Milky Way, don’t really care.
For the smallest galaxies, early conditions can decide whether they become visible galaxies or remain starless dark matter halos.
Future research
That sensitivity opens a clear path to testing early-universe physics with upcoming observations. Fattahi said:
Excitingly, in the near future we will have data from the Vera C. Rubin Observatory which will be able to find many more of these ultra faint dwarfs around the Milky Way.
Many astronomers hope Rubin can deliver a near-complete census of Milky Way satellite galaxies. And these simulations hint that this census may carry information far beyond our local neighborhood. Fattahi added:
Our work suggests that these upcoming observations of the very local universe will be able to constrain what the universe at its infancy looked like, something we currently cannot directly access with other observations.
The result is particularly relevant in the light of recent discoveries, by the James Webb Space Telescope, of galaxies in the early universe. Some of those galaxies are unexpectedly massive and bright.
If the early universe is producing surprises at large distances, then local relics from the same epoch – ultra-faint dwarfs – may provide an additional route to understanding what happened, according to Dr Fattahi.
Looking ahead, Dr Fattahi’s team plans to tackle questions that are still open in modern galaxy and structure formation. For example, where did the very first generation of stars form in the universe? Or what do the properties of ultra-faint dwarf galaxies tell us about the nature of dark matter?
Bottom line: Ultra-faint dwarf galaxies preserve clues to early-universe conditions, acting as cosmic fossils. Simulations show early radiation shaped whether these tiny galaxies formed stars or stayed dark.
Figure A shows a dark matter map in our neighborhood of the universe. The 2 blobs are dark matter halos of the Milky Way and Andromeda galaxies. Figure B zooms in to show a small dark matter clump about 700 million years after the Big Bang. Then C-1 and C-2 are stars and gas in the simulated ultra-faint dwarf galaxy. These show different radiation levels shortly after the Big Bang. Ultra-faint dwarf galaxies change their properties depending on which radiation is used. The scale on each image is in units of light-years. Image via Royal Astronomical Society/ J Sureda/ A Fattahi/ S Brown/ S Avraham. Attribution (CC BY 4.0).
Ultra-faint dwarf galaxies – tiny satellites of the Milky Way – act as cosmic fossils. They preserve clues about radiation and star formation in the early universe.
New high-resolution simulations show these faint galaxies are extremely sensitive to early-universe conditions. Those conditions determined whether small dark matter halos formed stars or stayed dark.
Future observations from the Vera C. Rubin Observatory could use these galaxies to reconstruct the universe’s earliest climate.
Ultra-faint dwarf galaxies show state of the early universe
Ultra-faint dwarf galaxies – tiny satellite galaxies orbiting the Milky Way – have long been seen as cosmic fossils.
Now, a new study published April 24, 2026, in Monthly Notices of the Royal Astronomical Society uses an unprecedented set of simulations to show just how powerfully these faint systems can reflect the conditions of the early universe. And it tells us why some galaxies grew and others did not.
These little galaxies could also reveal what the universe’s earliest ‘climate’ was like. For example, it could show the level of radiation and how this impacted whether and where stars formed.
Astronomers often describe dwarf galaxies as small cousins of the Milky Way. They form in small dark matter halos predicted by the standard model of cosmology. The faintest examples of such systems are extreme in both size and fragility. And they lie on the boundary of our knowledge about galaxy formation and dark matter.
Simulating tiny galaxies
Associate professor Azadeh Fattahi, of the Oskar Klein Centre (OKC) in Stockholm, led the new study with the LYRA collaboration and in collaboration with Durham University and the University of Hawaii. Fattahi said:
In this work we presented a brand-new suite of cosmological simulations focused on the faintest galaxies in the universe, with an unprecedented resolution. These are by far the largest sample of such galaxies ever simulated at these resolutions. The smallest galaxies are called ultra-faint dwarf galaxies, which are a million times less massive than the Milky Way or even smaller. Due to their small size these galaxies have proven very difficult to model and simulate.
This new simulation suite represents a major step forward, enabling a systematic view of how these galaxies form and evolve.
A down-to-earth analogy
Shaun Brown led the study while working at OKC and Durham University. Brown said:
A useful analogy is to plants and crops and how they grow is sensitive to the weather conditions. In the same way that the yield of a crop in summer can indirectly tell you a lot about what the weather in spring must have been like, the properties of faint dwarf galaxies today can tell us a lot about the conditions, or weather, of the universe at a much earlier time.
What makes the results especially timely is that the simulations do more than reproduce faint dwarf galaxies. They suggest that these local objects can act as a probe of the universe’s earliest ‘climate’. The team explored how different assumptions about the early radiation environment influence which small dark matter haloes manage to form stars at all. Brown explained:
In the paper we studied two different assumptions about the properties of the early universe when it was less than 500 million years old, to understand the effect on the properties of these small galaxies today when the universe is 13 billion years old. We found that these small ultra-faint galaxies are very sensitive to these changes, while more massive galaxies, like our Milky Way, don’t really care.
For the smallest galaxies, early conditions can decide whether they become visible galaxies or remain starless dark matter halos.
Future research
That sensitivity opens a clear path to testing early-universe physics with upcoming observations. Fattahi said:
Excitingly, in the near future we will have data from the Vera C. Rubin Observatory which will be able to find many more of these ultra faint dwarfs around the Milky Way.
Many astronomers hope Rubin can deliver a near-complete census of Milky Way satellite galaxies. And these simulations hint that this census may carry information far beyond our local neighborhood. Fattahi added:
Our work suggests that these upcoming observations of the very local universe will be able to constrain what the universe at its infancy looked like, something we currently cannot directly access with other observations.
The result is particularly relevant in the light of recent discoveries, by the James Webb Space Telescope, of galaxies in the early universe. Some of those galaxies are unexpectedly massive and bright.
If the early universe is producing surprises at large distances, then local relics from the same epoch – ultra-faint dwarfs – may provide an additional route to understanding what happened, according to Dr Fattahi.
Looking ahead, Dr Fattahi’s team plans to tackle questions that are still open in modern galaxy and structure formation. For example, where did the very first generation of stars form in the universe? Or what do the properties of ultra-faint dwarf galaxies tell us about the nature of dark matter?
Bottom line: Ultra-faint dwarf galaxies preserve clues to early-universe conditions, acting as cosmic fossils. Simulations show early radiation shaped whether these tiny galaxies formed stars or stayed dark.
View larger. | This image compares Venus (left) with 3 possible atmospheres for Gliese 12 b, an exoplanet that’s 40 light-years away. Venus is now a hot and arid planet, despite the fact that it possibly started off with a similar amount of water as Earth. A new study questions how much water on exoplanets life would require. Image via NASA/ JPL-Caltech/ R. Hurt (Caltech-IPAC)/ University of Washington.
Life as we know it needs water to exist. But how much water does an exoplanet need to be habitable in the long term?
More water than previously thought is the answer suggested by a new study.
At least 20 to 50% of the water on Earth would be required. Otherwise, the planet might start losing water on its surface and become arid.
How much water does an exoplanet need to stay habitable?
Astronomers consider water to be essential for life as we know it to form on a given planet. But, unfortunately, not all watery worlds stay watery. Venus, according to some studies, once had as much water as Earth does … but is now scorching hot, arid, and lifeless.
A new study from researchers at the University of Washington in Seattle suggests that Venus starting out with slightly less water than Earth could have made all the difference. The researchers said on April 15, 2026, that this lack of water could have destabilized the cycle of carbon between the planet’s atmosphere and interior. This would have caused carbon dioxide to build up in the air, raising temperatures and causing more water to evaporate.
So how much water does a world need to stay habitable? The study suggests that a rocky Earth-sized planet would need at least 20 to 50% of the water in Earth’s oceans to avoid this fate. That should be enough to maintain the crucial carbon cycle, keeping water on the surface long enough to potentially give water-based life time to develop.
This applies to planets in the habitable zone of their stars in particular. That’s the region where temperatures could allow liquid water to exist to begin with.
Scientists have long focused on the habitable zone around stars in the search for life. That’s because this is where liquid water could exist on rocky planets. But that depends on other factors, too, such as the composition of the atmosphere (if there is one) and the planet itself. White-Gianella said:
When you are searching for life in the broad landscape of the universe with limited resources, you have to filter out some planets.
Carbon Cycle Imbalances on Arid Terrestrial Planets with Implications for Venus: iopscience.iop.org/article/10.3… -> Planets need more water to support life than scientists previously thought: https://ift.tt/ZBa4izS…
To try to determine how much water a planet needs to be habitable, the study focused on arid planets that likely only have a little water. White-Gianella explained:
We were interested in arid planets with very limited surface water inventory, far less than one Earth ocean. Many of these planets are in the habitable zone of their star, but we weren’t sure if they could actually be habitable.
The carbon cycle
Since some of those planets are in the habitable zone, could they be habitable even with less water?
The researchers found that it depends on something called the carbon cycle. This cycle, driven by water, exchanges carbon between the atmosphere and interior of the planet, over millions of years. This process helps stabilize temperatures on the surface of the planet.
How does it work? Volcanoes emit carbon dioxide. The carbon dioxide accumulates in the atmosphere. Eventually it falls back to Earth in rain. Subsequently, the rain erodes and chemically reacts with rocks. The runoff in rivers brings the carbon back to the ocean, where it sinks down to the seafloor. Carbon-rich oceanic plates then move below the continental plates. Finally, millions of years later, the carbon comes back up to the surface in the form of mountains.
Low water levels
But there’s a catch. What if water levels drop too low for rainfall to occur? The carbon removal segment of the cycle – erosion by rain – can no longer keep up with carbon emissions from volcanoes. As a result, carbon dioxide builds up in the atmosphere. And this could create a runaway greenhouse effect, with temperatures becoming too hot to sustain life. This is what scientists say happened with Venus. As White-Gianella noted:
So that, unfortunately, makes these arid planets within habitable zones unlikely to be good candidates for life.
Krissanen-Totton said:
This has implications for a lot of the potentially habitable real estate out there.
The new carbon model of the study, focusing on arid planets, is an update to previous models. Those models focused more on water and cooler planets. They included factors such as evaporation from sunlight. But they neglected other factors, such as wind. Krissanen-Totton explained:
These sophisticated, mechanistic models of the carbon cycle have emerged from people trying to understand how Earth’s thermostat has worked – or hasn’t – to regulate temperature through time.
The new results show that even if a planet starts out with lots of surface water, it can lose it later on if the carbon cycle is interrupted.
View larger. | Japan’s Akatsuki (Venus Climate Orbiter) spacecraft captured this view of Venus on October 24, 2018. Venus is a good analog for exoplanets that lose their water and become arid and inhospitable to life on their surfaces. Image via JAXA/ ISAS/ DARTS/ Kevin M. Gill (CC BY 2.0).
Venus as an exoplanet analog
We already know of one such planet, and it’s in our own solar system: Venus. Scientists think Venus once had much more water, maybe even oceans. But Venus has since lost that water. Why?
Today, Venus is scorching hot on its surface, too hot for life. The dense carbon dioxide atmosphere traps heat so it can’t escape.
The researchers in the new study suggest that Venus might have had slightly less water than Earth early on. This caused an imbalance in the carbon cycle. And as the carbon dioxide accumulated in the atmosphere, the temperature kept rising.
Venus is a good analog for the kinds of exoplanets the researchers studied. As White-Gianella noted:
It’s very unlikely that we will land something on the surface of an exoplanet in our lifetime, but Venus – our next-door neighbor – is arguably the best exoplanet analog.
Speaking of Venus, another study, from 2025, suggests that Venus actually has more water in its atmosphere than previously thought. It’s still fire and brimstone on the surface, but perhaps this water could help sustain microbes that scientists have postulated could survive higher up in the atmosphere.
Bottom line: How much water on exoplanets does life need? A new study suggests at least 20 to 50% of the water on Earth.
View larger. | This image compares Venus (left) with 3 possible atmospheres for Gliese 12 b, an exoplanet that’s 40 light-years away. Venus is now a hot and arid planet, despite the fact that it possibly started off with a similar amount of water as Earth. A new study questions how much water on exoplanets life would require. Image via NASA/ JPL-Caltech/ R. Hurt (Caltech-IPAC)/ University of Washington.
Life as we know it needs water to exist. But how much water does an exoplanet need to be habitable in the long term?
More water than previously thought is the answer suggested by a new study.
At least 20 to 50% of the water on Earth would be required. Otherwise, the planet might start losing water on its surface and become arid.
How much water does an exoplanet need to stay habitable?
Astronomers consider water to be essential for life as we know it to form on a given planet. But, unfortunately, not all watery worlds stay watery. Venus, according to some studies, once had as much water as Earth does … but is now scorching hot, arid, and lifeless.
A new study from researchers at the University of Washington in Seattle suggests that Venus starting out with slightly less water than Earth could have made all the difference. The researchers said on April 15, 2026, that this lack of water could have destabilized the cycle of carbon between the planet’s atmosphere and interior. This would have caused carbon dioxide to build up in the air, raising temperatures and causing more water to evaporate.
So how much water does a world need to stay habitable? The study suggests that a rocky Earth-sized planet would need at least 20 to 50% of the water in Earth’s oceans to avoid this fate. That should be enough to maintain the crucial carbon cycle, keeping water on the surface long enough to potentially give water-based life time to develop.
This applies to planets in the habitable zone of their stars in particular. That’s the region where temperatures could allow liquid water to exist to begin with.
Scientists have long focused on the habitable zone around stars in the search for life. That’s because this is where liquid water could exist on rocky planets. But that depends on other factors, too, such as the composition of the atmosphere (if there is one) and the planet itself. White-Gianella said:
When you are searching for life in the broad landscape of the universe with limited resources, you have to filter out some planets.
Carbon Cycle Imbalances on Arid Terrestrial Planets with Implications for Venus: iopscience.iop.org/article/10.3… -> Planets need more water to support life than scientists previously thought: https://ift.tt/ZBa4izS…
To try to determine how much water a planet needs to be habitable, the study focused on arid planets that likely only have a little water. White-Gianella explained:
We were interested in arid planets with very limited surface water inventory, far less than one Earth ocean. Many of these planets are in the habitable zone of their star, but we weren’t sure if they could actually be habitable.
The carbon cycle
Since some of those planets are in the habitable zone, could they be habitable even with less water?
The researchers found that it depends on something called the carbon cycle. This cycle, driven by water, exchanges carbon between the atmosphere and interior of the planet, over millions of years. This process helps stabilize temperatures on the surface of the planet.
How does it work? Volcanoes emit carbon dioxide. The carbon dioxide accumulates in the atmosphere. Eventually it falls back to Earth in rain. Subsequently, the rain erodes and chemically reacts with rocks. The runoff in rivers brings the carbon back to the ocean, where it sinks down to the seafloor. Carbon-rich oceanic plates then move below the continental plates. Finally, millions of years later, the carbon comes back up to the surface in the form of mountains.
Low water levels
But there’s a catch. What if water levels drop too low for rainfall to occur? The carbon removal segment of the cycle – erosion by rain – can no longer keep up with carbon emissions from volcanoes. As a result, carbon dioxide builds up in the atmosphere. And this could create a runaway greenhouse effect, with temperatures becoming too hot to sustain life. This is what scientists say happened with Venus. As White-Gianella noted:
So that, unfortunately, makes these arid planets within habitable zones unlikely to be good candidates for life.
Krissanen-Totton said:
This has implications for a lot of the potentially habitable real estate out there.
The new carbon model of the study, focusing on arid planets, is an update to previous models. Those models focused more on water and cooler planets. They included factors such as evaporation from sunlight. But they neglected other factors, such as wind. Krissanen-Totton explained:
These sophisticated, mechanistic models of the carbon cycle have emerged from people trying to understand how Earth’s thermostat has worked – or hasn’t – to regulate temperature through time.
The new results show that even if a planet starts out with lots of surface water, it can lose it later on if the carbon cycle is interrupted.
View larger. | Japan’s Akatsuki (Venus Climate Orbiter) spacecraft captured this view of Venus on October 24, 2018. Venus is a good analog for exoplanets that lose their water and become arid and inhospitable to life on their surfaces. Image via JAXA/ ISAS/ DARTS/ Kevin M. Gill (CC BY 2.0).
Venus as an exoplanet analog
We already know of one such planet, and it’s in our own solar system: Venus. Scientists think Venus once had much more water, maybe even oceans. But Venus has since lost that water. Why?
Today, Venus is scorching hot on its surface, too hot for life. The dense carbon dioxide atmosphere traps heat so it can’t escape.
The researchers in the new study suggest that Venus might have had slightly less water than Earth early on. This caused an imbalance in the carbon cycle. And as the carbon dioxide accumulated in the atmosphere, the temperature kept rising.
Venus is a good analog for the kinds of exoplanets the researchers studied. As White-Gianella noted:
It’s very unlikely that we will land something on the surface of an exoplanet in our lifetime, but Venus – our next-door neighbor – is arguably the best exoplanet analog.
Speaking of Venus, another study, from 2025, suggests that Venus actually has more water in its atmosphere than previously thought. It’s still fire and brimstone on the surface, but perhaps this water could help sustain microbes that scientists have postulated could survive higher up in the atmosphere.
Bottom line: How much water on exoplanets does life need? A new study suggests at least 20 to 50% of the water on Earth.
View at EarthSky Community Photos. | Frank Lu of Texas captured this image on February 5, 2025, and wrote: “Inspired by Deborah Byrd’s article in EarthSky’s Astronomy Essentials, I went out looking for the Lunar X and Lunar V on this 1st-quarter moon. I’m extremely pleased to find them.” Thank you, Frank!
Tonight’s 1st quarter moon is a perfect time to look for the Lunar X and V. It occurs overnight tonight at 2:32 UTC on April 24. So take a look!
Have you heard of Lunar X and Lunar V? They are famous optical features on the moon, visible through telescopes. So, when the moon’s terminator – or line between light and dark on the moon – is located in just the right place, you can see a letter X and a letter V on the moon’s surface. Are they a sign of an alien visitation? No. Rather, Lunar X is a great example of how lighting and topography can combine on a planet or moon to produce a pattern that seems familiar to the human eye.
In reality, the illusion of Lunar X is created by sunlight falling on the rims/ridges between the craters La Caille, Bianchini and Purbach. And the V is caused by light illuminating crater Ukert, along with several smaller craters.
View at EarthSky Community Photos. | Kannan A in Singapore wrote on April 19, 2021: “Upon a close look at the moon tonight, I realized that the Lunar X and Lunar V were clearly visible. These are transient lunar features visible on the lunar surface for about 4 hours once a month. They are most striking when they are visible on the shadow side of the terminator. But they will remain visible against the lunar surface even after the terminator has moved because they are brighter than the surrounding area.” Thank you, Kannan!
When are they visible?
Basically, people see Lunar X and Lunar V at each cycle of the moon, but only for a short time. In fact, they’re observable for about four hours around the 1st quarter moon phase.
View at EarthSky Community Photo. | Greg Redfern captured this image from Virginia on July 2, 2025, and wrote: “The lunar X & V showed up last night in great splendor … what a treat to see and image.” Thank you, Greg!View at EarthSky Community Photos. | Matthew Chin from Hong Kong, China, shared this image of the moon, where Lunar X and Lunar V are visible, on January 18, 2024. Thank you, Matthew!
Bottom line: Lunar X and Lunar V are optical features on the moon. They are visible through a telescope for several hours around the time of the 1st quarter moon.
View at EarthSky Community Photos. | Frank Lu of Texas captured this image on February 5, 2025, and wrote: “Inspired by Deborah Byrd’s article in EarthSky’s Astronomy Essentials, I went out looking for the Lunar X and Lunar V on this 1st-quarter moon. I’m extremely pleased to find them.” Thank you, Frank!
Tonight’s 1st quarter moon is a perfect time to look for the Lunar X and V. It occurs overnight tonight at 2:32 UTC on April 24. So take a look!
Have you heard of Lunar X and Lunar V? They are famous optical features on the moon, visible through telescopes. So, when the moon’s terminator – or line between light and dark on the moon – is located in just the right place, you can see a letter X and a letter V on the moon’s surface. Are they a sign of an alien visitation? No. Rather, Lunar X is a great example of how lighting and topography can combine on a planet or moon to produce a pattern that seems familiar to the human eye.
In reality, the illusion of Lunar X is created by sunlight falling on the rims/ridges between the craters La Caille, Bianchini and Purbach. And the V is caused by light illuminating crater Ukert, along with several smaller craters.
View at EarthSky Community Photos. | Kannan A in Singapore wrote on April 19, 2021: “Upon a close look at the moon tonight, I realized that the Lunar X and Lunar V were clearly visible. These are transient lunar features visible on the lunar surface for about 4 hours once a month. They are most striking when they are visible on the shadow side of the terminator. But they will remain visible against the lunar surface even after the terminator has moved because they are brighter than the surrounding area.” Thank you, Kannan!
When are they visible?
Basically, people see Lunar X and Lunar V at each cycle of the moon, but only for a short time. In fact, they’re observable for about four hours around the 1st quarter moon phase.
View at EarthSky Community Photo. | Greg Redfern captured this image from Virginia on July 2, 2025, and wrote: “The lunar X & V showed up last night in great splendor … what a treat to see and image.” Thank you, Greg!View at EarthSky Community Photos. | Matthew Chin from Hong Kong, China, shared this image of the moon, where Lunar X and Lunar V are visible, on January 18, 2024. Thank you, Matthew!
Bottom line: Lunar X and Lunar V are optical features on the moon. They are visible through a telescope for several hours around the time of the 1st quarter moon.
