1st ultra-faint Milky Way satellite galaxy found by Rubin

This starfield shows the newly discovered Milky Way satellite galaxy at the center. The point of light at left marked by the star shape indicates a star that was crucial in determining the distance to this little galaxy. Image via William Cerny/ Rubin Observatory/ arXiv.

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New Milky Way satellite galaxy

This month, scientists using the preliminary data from the Vera C. Rubin Observatory said they had already discovered Rubin’s first ultra-faint satellite galaxy orbiting our home galaxy, the Milky Way. They’ve dubbed the new galaxy Aquarius IV. It’s one of the faintest of the roughly 60 little galaxies currently known to be orbiting (or closely associated with) the Milky Way.

The scientists say this discovery offers an early glimpse of the new observatory’s power to probe the universe.

The Vera C. Rubin Observatory – on the summit of Cerro Pachón in northern Chile – features a 3.2-gigapixel camera, roughly the size of a small car, making it the largest digital camera ever built for astronomy. This camera’s resolution is so high that displaying a single full-size image would require hundreds of 4K ultra-HD television screens. Using this camera, astronomers began a 10-year Legacy Survey of Space and Time (LSST) in June 2026.

The new satellite galaxy is one of the first of what scientists expect will be many discoveries. Researchers found the galaxy in Rubin’s Early Data Preview 2 dataset.

The researchers, led by William Cerny of Yale University, published their study in arXiv on August 4, 2026. This study has not yet been peer-reviewed.

Tiny galaxy hidden in Milky Way’s outskirts

Aquarius IV lies about 355,000 light-years from Earth, in the Milky Way’s outer halo. After detecting the galaxy in the Rubin data, the team confirmed the discovery in archival images from a second astronomical camera located in Chile, the Dark Energy Camera installed at the Victor M. Blanco 4-meter (13-foot) Telescope at Cerro Tololo.

Astronomers believe Aquarius IV is an ultra-faint dwarf galaxy. The paper said these types of galaxies:

… are the least luminous, least chemically enriched and most dark matter-dominated galaxies known, making them powerful probes of galaxy formation and dark matter physics.

Scientists found the first ultra-faint dwarf galaxy orbiting the Milky Way about 20 years ago. Today, there are roughly 60 other discoveries. But astronomers believe there are still hundreds of small galaxies near our Milky Way left to find.

And it’s already looking like Rubin will have a good chance of discovering them. The Early Data Preview 2 doesn’t even come from the start of the LSST survey. It came from a testing phase, before the survey began, between April 2025 and January 2026.

What else do we know about Aquarius IV?

Aquarius IV has an apparent magnitude of 18.3. That is incredibly faint, but – by stacking images and filtering out “noise” – the LSST survey can see even fainter objects. Still, galaxies like Aquarius IV are incredibly dim; they consist of diffuse stars of low luminosity. So they’re challenging to find!

The stars in Aquarius IV are poor in heavy elements, indicating that they are quite ancient, perhaps about 13 billion years old. That would mean they formed early in the universe’s history.

But the researchers caution that their classification of Aquarius IV as an ultra-faint dwarf galaxy is still preliminary. There is a chance it could be an unusually large globular cluster. The researchers said they need to do more observations to get spectroscopic measurements from more of its stars before they can confirm its true nature.

Artist’s concept of our Milky Way galaxy. The galaxy’s halo is a large sphere encompassing the entire Milky Way. Inside this sphere, astronomers said they have just discovered an ultra-faint satellite galaxy. Image via NASA.

Why ultra-faint galaxies matter

Ultra-faint dwarf galaxies are the least luminous and least chemically enriched (oldest) galaxies known. They are also believed to be the most dark matter-dominated. Dark matter is a mysterious substance believed to make up roughly 85% of all the universe’s matter (or 27% of the total universe). Dark energy, meanwhile, makes up the majority of the universe.

Astronomers study ultra-faint dwarf galaxies in part because they hold clues about how the first galaxies formed and how dark matter shaped the early universe.

Just the beginning for Rubin

Aquarius IV is already an exciting discovery using just the earliest observations from the Rubin Observatory. As the paper says:

Aquarius IV is among the faintest known Milky Way satellites in the distant halo, demonstrating Rubin’s ability to reveal ultra-faint satellites at the limits of existing surveys, even in its initial phases of operation. The sensitivity of Rubin LSST will steadily increase, and systems similar to Aquarius IV are expected to be detectable with more than 85% efficiency using the same search algorithm applied here. Rubin LSST thus stands poised to revolutionize the census of ultra-faint Milky Way satellites.

Bottom line: The Vera C. Rubin Observatory has only just begun its survey, yet it has already discovered Aquarius IV, an ultra-faint satellite galaxy of the Milky Way.

Source: Discovery of the Distant, Ultra-Faint Milky Way Satellite Aquarius IV with the Vera C. Rubin Observatory Early Data Preview 2

Read more: Rubin Observatory begins 10-year timelapse of the universe

Read more: Rubin Observatory launches real-time alert system

The post 1st ultra-faint Milky Way satellite galaxy found by Rubin first appeared on EarthSky.

from EarthSky https://ift.tt/DMH76Fl

This starfield shows the newly discovered Milky Way satellite galaxy at the center. The point of light at left marked by the star shape indicates a star that was crucial in determining the distance to this little galaxy. Image via William Cerny/ Rubin Observatory/ arXiv.

You deserve a daily dose of good news. For the latest in science and the night sky, subscribe to EarthSky’s free daily newsletter.

New Milky Way satellite galaxy

This month, scientists using the preliminary data from the Vera C. Rubin Observatory said they had already discovered Rubin’s first ultra-faint satellite galaxy orbiting our home galaxy, the Milky Way. They’ve dubbed the new galaxy Aquarius IV. It’s one of the faintest of the roughly 60 little galaxies currently known to be orbiting (or closely associated with) the Milky Way.

The scientists say this discovery offers an early glimpse of the new observatory’s power to probe the universe.

The Vera C. Rubin Observatory – on the summit of Cerro Pachón in northern Chile – features a 3.2-gigapixel camera, roughly the size of a small car, making it the largest digital camera ever built for astronomy. This camera’s resolution is so high that displaying a single full-size image would require hundreds of 4K ultra-HD television screens. Using this camera, astronomers began a 10-year Legacy Survey of Space and Time (LSST) in June 2026.

The new satellite galaxy is one of the first of what scientists expect will be many discoveries. Researchers found the galaxy in Rubin’s Early Data Preview 2 dataset.

The researchers, led by William Cerny of Yale University, published their study in arXiv on August 4, 2026. This study has not yet been peer-reviewed.

Tiny galaxy hidden in Milky Way’s outskirts

Aquarius IV lies about 355,000 light-years from Earth, in the Milky Way’s outer halo. After detecting the galaxy in the Rubin data, the team confirmed the discovery in archival images from a second astronomical camera located in Chile, the Dark Energy Camera installed at the Victor M. Blanco 4-meter (13-foot) Telescope at Cerro Tololo.

Astronomers believe Aquarius IV is an ultra-faint dwarf galaxy. The paper said these types of galaxies:

… are the least luminous, least chemically enriched and most dark matter-dominated galaxies known, making them powerful probes of galaxy formation and dark matter physics.

Scientists found the first ultra-faint dwarf galaxy orbiting the Milky Way about 20 years ago. Today, there are roughly 60 other discoveries. But astronomers believe there are still hundreds of small galaxies near our Milky Way left to find.

And it’s already looking like Rubin will have a good chance of discovering them. The Early Data Preview 2 doesn’t even come from the start of the LSST survey. It came from a testing phase, before the survey began, between April 2025 and January 2026.

What else do we know about Aquarius IV?

Aquarius IV has an apparent magnitude of 18.3. That is incredibly faint, but – by stacking images and filtering out “noise” – the LSST survey can see even fainter objects. Still, galaxies like Aquarius IV are incredibly dim; they consist of diffuse stars of low luminosity. So they’re challenging to find!

The stars in Aquarius IV are poor in heavy elements, indicating that they are quite ancient, perhaps about 13 billion years old. That would mean they formed early in the universe’s history.

But the researchers caution that their classification of Aquarius IV as an ultra-faint dwarf galaxy is still preliminary. There is a chance it could be an unusually large globular cluster. The researchers said they need to do more observations to get spectroscopic measurements from more of its stars before they can confirm its true nature.

Artist’s concept of our Milky Way galaxy. The galaxy’s halo is a large sphere encompassing the entire Milky Way. Inside this sphere, astronomers said they have just discovered an ultra-faint satellite galaxy. Image via NASA.

Why ultra-faint galaxies matter

Ultra-faint dwarf galaxies are the least luminous and least chemically enriched (oldest) galaxies known. They are also believed to be the most dark matter-dominated. Dark matter is a mysterious substance believed to make up roughly 85% of all the universe’s matter (or 27% of the total universe). Dark energy, meanwhile, makes up the majority of the universe.

Astronomers study ultra-faint dwarf galaxies in part because they hold clues about how the first galaxies formed and how dark matter shaped the early universe.

Just the beginning for Rubin

Aquarius IV is already an exciting discovery using just the earliest observations from the Rubin Observatory. As the paper says:

Aquarius IV is among the faintest known Milky Way satellites in the distant halo, demonstrating Rubin’s ability to reveal ultra-faint satellites at the limits of existing surveys, even in its initial phases of operation. The sensitivity of Rubin LSST will steadily increase, and systems similar to Aquarius IV are expected to be detectable with more than 85% efficiency using the same search algorithm applied here. Rubin LSST thus stands poised to revolutionize the census of ultra-faint Milky Way satellites.

Bottom line: The Vera C. Rubin Observatory has only just begun its survey, yet it has already discovered Aquarius IV, an ultra-faint satellite galaxy of the Milky Way.

Source: Discovery of the Distant, Ultra-Faint Milky Way Satellite Aquarius IV with the Vera C. Rubin Observatory Early Data Preview 2

Read more: Rubin Observatory begins 10-year timelapse of the universe

Read more: Rubin Observatory launches real-time alert system

The post 1st ultra-faint Milky Way satellite galaxy found by Rubin first appeared on EarthSky.

from EarthSky https://ift.tt/DMH76Fl

Give me 5 minutes and I’ll give you Saturn in 2026

The Cassini spacecraft orbited Saturn from 2004 to 2017. This image stemmed from a Cassini highlight, when it executed a fantastic series of maneuvers, diving repeatedly between the planet’s outer atmosphere and inner rings. The image is from high above Saturn, looking down toward its north pole. Image via software engineer Gordan Ugarkovic/ NASA.

In mid-August 2026, Saturn is rising in the middle of the night. Watch for it around midnight, ascending at the sunrise point in your sky. It’ll look like a bright golden “star.” By dawn, Saturn – still on the sun’s path – will be at its highest in your sky. Or watch for Saturn near the moon on August 29 and 30.

Saturn is the 6th planet outward from the sun and the farthest planet easily visible to the unaided eye. It’s the faintest and slowest-moving of the bright planets. You need a telescope to see the planet’s rings, but Saturn is also fun to watch with the eye alone. You’ll find it shining with a steady light, in a creamy golden color.

Saturn takes almost 30 years to orbit the sun. So it moves more slowly than the other bright planets in front of the fixed stars. The ancient Assyrians called Saturn Lubad-sag-uš, often translated as the oldest of the old sheep. It’s easy to imagine why, if you consider Saturn’s slow movement in front of the stars. Because of its nearly 30-year orbit, it takes nearly 30 years to complete one journey our sky, traveling through all the constellations of the zodiac. It really does seem to amble across the sky like an old sheep.

And, unlike the other bright planets, Saturn isn’t showy to the eye alone. It’s the hardest bright planet to recognize.

But moon is a handy tool. Look for the moon near Saturn on August 29 and 30, 2026. And it’ll be near the full moon again on September 27, and every month it is visible. To find Saturn near the moon every month of the year (except when it is behind the sun), visit EarthSky’s night sky guide.

And keep reading to learn the best time of 2026 to look for Saturn.

The waning gibbous moon joins Saturn on the evenings of August 29 and 30. You can catch them until dawn. Chart via EarthSky.

Saturn closest, brightest, opposite sun on October 4

The best time of year to see an outer planet, like Saturn, are the months around that planet’s yearly opposition. That’s when Earth will go between the sun and that outer world. The planet will appear opposite the sun in our sky, rising into view at a convenient hour for viewing.

In 2026, Saturn will come to opposition on October 4. So the months around October are best for viewing the planet this year.

Because we’re going between Saturn and the sun then, October 4 – the opposition date – will feature the ringed planet approximately at its closest to Earth. Because it’s closest, it’ll appear at its brightest in our sky. Saturn is the faintest of the bright planets. It’s still pretty bright, but, normally, you wouldn’t pick it out from among the stars.

But around September, October and November, you can view Saturn fairly easily, because Saturn will appear as bright as the brightest stars.

Since we pass Saturn – the 6th planet outward from the sun – from an inside track around the sun, the ringed planet will look as if it’s going backward (retrograde) for a time, in front of the fixed stars of the zodiac. In 2026, Saturn retrogrades from July 27 until December 11. That’s when it moves westward in front of the stars, in contrast to its regular motion, toward the east in front of the stars.

When Saturn started its retrograde (westward) movement in front of the backdrop stars of the zodiac on July 27, it was among the stars of Aquarius the Water Bearer. By the end of Saturn’s retrograde on December 11, it’ll lie among the stars of Cetus the Whale. It’ll remain in Cetus the rest of 2026.

Saturn’s yearly opposition happens about two weeks later with each passing year. The 2024 opposition happened on September 8. The 2025 opposition happened on September 21. And the 2026 opposition will be on October 4. And next year? Opposition for Saturn in 2027 will take place October 18.

So you see that Saturn – like most objects in the heavens – is really very orderly in its comings and goings in our sky. Once you learn to identify it, you can recognize it from year to year.

Opposition happens when Earth flies between an outer planet, like Saturn, and the sun. In 2026, Saturn’s opposition comes on October 4. Illustration via Heavens-Above. Used with permission.

But how can you recognize it?

Like all planets, Saturn is lovely to gaze upon and think about. It’s a real place, after all, not just a light in the sky. Plus, Saturn’s brightness waxes and wanes in a subtle way throughout every year, making it fun to watch. But how can you recognize Saturn?

As we said above, the best way is to start with the nights when the moon will be passing near. To find out when this will be: visit EarthSky’s night sky guide.

But what if you can’t wait for the moon? Here are some tips:

• Think about the path the sun travels across your sky. That path is called the ecliptic. On EarthSky charts, we nearly always represent that path by a green line. So – wherever you are on Earth – you will look along the sun’s path for Saturn.
• Look along that path for bright lights. Saturn may be the faintest of the bright planets, but it’s as bright as the brightest stars.
• Notice the twinkling of the stars. Stars twinkle because they are so far away. Through earthly telescopes, even, unless some special technique is being used, stars look like pinpoints. But Saturn is vastly closer than the stars. Through telescopes it looks like a golden (ring-encircled) disk. Light waves from one side of that disk cancel out light waves from the other side. So Saturn shines steadily!
• Watch for its golden color. Yes. Saturn appears golden to the eye. A golden, steady light – located along the sun’s path across the sky – is likely Saturn.

Can you see the rings of Saturn if you look with the eye alone? No, you need a small telescope to see the rings. But Saturn is still beautiful to the eye. Once you learn to spot it, you’ll find a great source of contentment in recognizing it year after year.

The Cassini spacecraft ended its mission in 2017. This Cassini image is from December 18, 2016. It shows a level of detail in Saturn’s rings twice as high as had ever been observed before. Wow! Image via NASA. Read more about Cassini’s epic final year at Saturn.

Saturn from the Southern Hemisphere

Via Daniel Gaussen, Founder & Guide – Stargaze Mackenzie – Twizel, New Zealand

From the Northern Hemisphere, the sun’s path arcs across the southern sky. But, from the Southern Hemisphere, you will look north rather than south to follow the sun and planets along the ecliptic. How high the sun’s path appears to you depends on your latitude, and on which part of the ecliptic you’re looking toward.

From Twizel, New Zealand, at about 44 degrees south latitude, different parts of the ecliptic can reach anywhere from about 23 degrees to nearly 70 degrees above the northern horizon as they cross the meridian. Farther north, from Auckland or much of Australia, parts of the ecliptic can climb higher still.

As Saturn spends nearly 30 years moving around our sky, it gradually passes through sections of the ecliptic that appear higher or lower in our sky. At its 2026 opposition, Saturn will reach about 44 degrees high from Twizel, 51 degrees from Auckland and 54 degrees from Sydney, comfortably above the horizon and offering good views through a telescope.

So, for much of the Southern Hemisphere, Saturn will be reasonably high above the northern horizon around its October 2026 opposition. It will rise around sunset in the east-northeast, climb across the northern sky and culminate (reach its highest point) due north around midnight, before heading toward the west-northwest.

Over the decades, Saturn’s altitude at opposition gradually changes as it makes its long journey through the zodiac, a planetary cycle you can watch unfold over a lifetime.

Where will Saturn be in the last few months of 2026?

Saturn is nearly always somewhere in our sky, for most of every year. In the second half 2026, as Earth moves away from Saturn in its orbit, we’ll see Saturn shift its location in our evening sky, rising earlier each night.

After Saturn’s opposition in October 2026, Saturn will appear farther to the west as darkness falls each month thereafter.

Finally, in March of 2027, Saturn will disappear in the western twilight after sunset.

One last thing, for you telescope users: the south side of Saturn’s rings are facing in Earth’s direction. They’ll have a -7.5-degree tilt around opposition.

View at EarthSky Community Photos. | John Nelson of Puget Sound, Washington, submitted this composite image and wrote: “A composite of some of my images of Saturn over the last 6 years showing how the angle of Saturn’s rings to Earth have been slowly decreasing. Saturn’s ring angle toward Earth cycles over a 13- to 15-year period going from nearly fully open to edge on then back again.” Thank you, John.

Bottom line: The best time for viewing the planet Saturn in 2026 is here. The ringed planet will be at its brightest and in the sky all night, or nearly so. Why? Because we’ll pass between Saturn and the sun on October 4.

The post Give me 5 minutes and I’ll give you Saturn in 2026 first appeared on EarthSky.

from EarthSky https://ift.tt/k2QDUIn

The Cassini spacecraft orbited Saturn from 2004 to 2017. This image stemmed from a Cassini highlight, when it executed a fantastic series of maneuvers, diving repeatedly between the planet’s outer atmosphere and inner rings. The image is from high above Saturn, looking down toward its north pole. Image via software engineer Gordan Ugarkovic/ NASA.

In mid-August 2026, Saturn is rising in the middle of the night. Watch for it around midnight, ascending at the sunrise point in your sky. It’ll look like a bright golden “star.” By dawn, Saturn – still on the sun’s path – will be at its highest in your sky. Or watch for Saturn near the moon on August 29 and 30.

Saturn is the 6th planet outward from the sun and the farthest planet easily visible to the unaided eye. It’s the faintest and slowest-moving of the bright planets. You need a telescope to see the planet’s rings, but Saturn is also fun to watch with the eye alone. You’ll find it shining with a steady light, in a creamy golden color.

Saturn takes almost 30 years to orbit the sun. So it moves more slowly than the other bright planets in front of the fixed stars. The ancient Assyrians called Saturn Lubad-sag-uš, often translated as the oldest of the old sheep. It’s easy to imagine why, if you consider Saturn’s slow movement in front of the stars. Because of its nearly 30-year orbit, it takes nearly 30 years to complete one journey our sky, traveling through all the constellations of the zodiac. It really does seem to amble across the sky like an old sheep.

And, unlike the other bright planets, Saturn isn’t showy to the eye alone. It’s the hardest bright planet to recognize.

But moon is a handy tool. Look for the moon near Saturn on August 29 and 30, 2026. And it’ll be near the full moon again on September 27, and every month it is visible. To find Saturn near the moon every month of the year (except when it is behind the sun), visit EarthSky’s night sky guide.

And keep reading to learn the best time of 2026 to look for Saturn.

The waning gibbous moon joins Saturn on the evenings of August 29 and 30. You can catch them until dawn. Chart via EarthSky.

Saturn closest, brightest, opposite sun on October 4

The best time of year to see an outer planet, like Saturn, are the months around that planet’s yearly opposition. That’s when Earth will go between the sun and that outer world. The planet will appear opposite the sun in our sky, rising into view at a convenient hour for viewing.

In 2026, Saturn will come to opposition on October 4. So the months around October are best for viewing the planet this year.

Because we’re going between Saturn and the sun then, October 4 – the opposition date – will feature the ringed planet approximately at its closest to Earth. Because it’s closest, it’ll appear at its brightest in our sky. Saturn is the faintest of the bright planets. It’s still pretty bright, but, normally, you wouldn’t pick it out from among the stars.

But around September, October and November, you can view Saturn fairly easily, because Saturn will appear as bright as the brightest stars.

Since we pass Saturn – the 6th planet outward from the sun – from an inside track around the sun, the ringed planet will look as if it’s going backward (retrograde) for a time, in front of the fixed stars of the zodiac. In 2026, Saturn retrogrades from July 27 until December 11. That’s when it moves westward in front of the stars, in contrast to its regular motion, toward the east in front of the stars.

When Saturn started its retrograde (westward) movement in front of the backdrop stars of the zodiac on July 27, it was among the stars of Aquarius the Water Bearer. By the end of Saturn’s retrograde on December 11, it’ll lie among the stars of Cetus the Whale. It’ll remain in Cetus the rest of 2026.

Saturn’s yearly opposition happens about two weeks later with each passing year. The 2024 opposition happened on September 8. The 2025 opposition happened on September 21. And the 2026 opposition will be on October 4. And next year? Opposition for Saturn in 2027 will take place October 18.

So you see that Saturn – like most objects in the heavens – is really very orderly in its comings and goings in our sky. Once you learn to identify it, you can recognize it from year to year.

Opposition happens when Earth flies between an outer planet, like Saturn, and the sun. In 2026, Saturn’s opposition comes on October 4. Illustration via Heavens-Above. Used with permission.

But how can you recognize it?

Like all planets, Saturn is lovely to gaze upon and think about. It’s a real place, after all, not just a light in the sky. Plus, Saturn’s brightness waxes and wanes in a subtle way throughout every year, making it fun to watch. But how can you recognize Saturn?

As we said above, the best way is to start with the nights when the moon will be passing near. To find out when this will be: visit EarthSky’s night sky guide.

But what if you can’t wait for the moon? Here are some tips:

• Think about the path the sun travels across your sky. That path is called the ecliptic. On EarthSky charts, we nearly always represent that path by a green line. So – wherever you are on Earth – you will look along the sun’s path for Saturn.
• Look along that path for bright lights. Saturn may be the faintest of the bright planets, but it’s as bright as the brightest stars.
• Notice the twinkling of the stars. Stars twinkle because they are so far away. Through earthly telescopes, even, unless some special technique is being used, stars look like pinpoints. But Saturn is vastly closer than the stars. Through telescopes it looks like a golden (ring-encircled) disk. Light waves from one side of that disk cancel out light waves from the other side. So Saturn shines steadily!
• Watch for its golden color. Yes. Saturn appears golden to the eye. A golden, steady light – located along the sun’s path across the sky – is likely Saturn.

Can you see the rings of Saturn if you look with the eye alone? No, you need a small telescope to see the rings. But Saturn is still beautiful to the eye. Once you learn to spot it, you’ll find a great source of contentment in recognizing it year after year.

The Cassini spacecraft ended its mission in 2017. This Cassini image is from December 18, 2016. It shows a level of detail in Saturn’s rings twice as high as had ever been observed before. Wow! Image via NASA. Read more about Cassini’s epic final year at Saturn.

Saturn from the Southern Hemisphere

Via Daniel Gaussen, Founder & Guide – Stargaze Mackenzie – Twizel, New Zealand

From the Northern Hemisphere, the sun’s path arcs across the southern sky. But, from the Southern Hemisphere, you will look north rather than south to follow the sun and planets along the ecliptic. How high the sun’s path appears to you depends on your latitude, and on which part of the ecliptic you’re looking toward.

From Twizel, New Zealand, at about 44 degrees south latitude, different parts of the ecliptic can reach anywhere from about 23 degrees to nearly 70 degrees above the northern horizon as they cross the meridian. Farther north, from Auckland or much of Australia, parts of the ecliptic can climb higher still.

As Saturn spends nearly 30 years moving around our sky, it gradually passes through sections of the ecliptic that appear higher or lower in our sky. At its 2026 opposition, Saturn will reach about 44 degrees high from Twizel, 51 degrees from Auckland and 54 degrees from Sydney, comfortably above the horizon and offering good views through a telescope.

So, for much of the Southern Hemisphere, Saturn will be reasonably high above the northern horizon around its October 2026 opposition. It will rise around sunset in the east-northeast, climb across the northern sky and culminate (reach its highest point) due north around midnight, before heading toward the west-northwest.

Over the decades, Saturn’s altitude at opposition gradually changes as it makes its long journey through the zodiac, a planetary cycle you can watch unfold over a lifetime.

Where will Saturn be in the last few months of 2026?

Saturn is nearly always somewhere in our sky, for most of every year. In the second half 2026, as Earth moves away from Saturn in its orbit, we’ll see Saturn shift its location in our evening sky, rising earlier each night.

After Saturn’s opposition in October 2026, Saturn will appear farther to the west as darkness falls each month thereafter.

Finally, in March of 2027, Saturn will disappear in the western twilight after sunset.

One last thing, for you telescope users: the south side of Saturn’s rings are facing in Earth’s direction. They’ll have a -7.5-degree tilt around opposition.

View at EarthSky Community Photos. | John Nelson of Puget Sound, Washington, submitted this composite image and wrote: “A composite of some of my images of Saturn over the last 6 years showing how the angle of Saturn’s rings to Earth have been slowly decreasing. Saturn’s ring angle toward Earth cycles over a 13- to 15-year period going from nearly fully open to edge on then back again.” Thank you, John.

Bottom line: The best time for viewing the planet Saturn in 2026 is here. The ringed planet will be at its brightest and in the sky all night, or nearly so. Why? Because we’ll pass between Saturn and the sun on October 4.

The post Give me 5 minutes and I’ll give you Saturn in 2026 first appeared on EarthSky.

from EarthSky https://ift.tt/k2QDUIn

Is Ophiuchus the 13th constellation of the zodiac?

If you’re in the Northern Hemisphere, look southward on your summer evenings for mighty Ophiuchus the Serpent Bearer. It’s surrounded by the constellations Serpens Cauda and Serpens Caput. Chart via EarthSky.

Ophiuchus, the unofficial 13th constellation of the zodiac

If you were born somewhere between November 30 and December 18, chances are the sun was in the constellation Ophiuchus the Serpent Bearer. Therefore, your “sign” should be Ophiuchus. But, of course, Ophiuchus is not an official constellation of the zodiac, nor will you find it in horoscopes. Ophiuchus the Serpent Bearer is a large constellation that you can spot near the southern horizon from the Northern Hemisphere during July, August and September evenings. The Serpent Bearer is standing on the Scorpion and its red star Antares.

From the Southern Hemisphere, Ophiuchus is closer to overhead. Ophiuchus’ brightest star is Rasalhague.

The official boundary lines for all 88 constellations were drawn up by the International Astronomical Union (IAU) in the 1930s.

Signs versus constellations

Poor Ophiuchus. Nobody ever claims him as a birth sign, despite the fact that the ecliptic runs across him, too. After all, the band of the zodiac extends some 8 degrees north and south of the ecliptic, spanning a total of 16 degrees in width. And the constellations are not evenly spaced along this band in our sky. The signs of the zodiac are familiar to all who read online astrology advice. There are 12 familiar signs of the zodiac, but no Ophiuchus.

Yet the moon and planets do regularly move within the boundaries of Ophiuchus. And so does the sun. The sun is in front of Ophiuchus from about November 30 to December 18 each year.

The sun is said to enter the sign Sagittarius around November 21, or whenever the sun is precisely 30 degrees west of the December solstice point. And then the sun then enters the sign Capricorn on the December 21 solstice. So the sun passes through the “sign” Sagittarius for the period before and up to the December solstice, irrespective of the fact that the sun is actually shining in front of the constellation Ophiuchus from November 30 to December 18.

By the way, the December solstice point moves one degree westward in front of the zodiacal constellations – or backdrop stars – in about 72 years. This means that the December solstice point will finally move into the constellation Ophiuchus by the year 2269.

Ophiuchus holding the serpent, Serpens, as depicted in Urania’s Mirror, a set of constellation cards published in London circa 1825. Image via Adam Cuerden/ Wikipedia.

When and where to locate Ophiuchus

The best time to observe Ophiuchus is during a Northern Hemisphere summer (Southern Hemisphere winter). From the Northern Hemisphere, late July and early August present this constellation high in the southern sky at nightfall and early evening. It’s in the southwest sky on autumn evenings in the Northern Hemisphere.

This rather large constellation fills the area of sky to the north of the constellation Scorpius the Scorpion and to the south of the constellation Hercules the Strongman. If you’re familiar with Scorpius’ brightest star Antares, try star-hopping to Ophiuchus from this ruddy gem of a star. The head of Ophiuchus is marked by the star Rasalhague (Alpha Ophiuchi).

View larger. | Ophiuchus the Serpent Bearer. Image via Wikipedia (CC BY 3.0).

Ophiuchus is joined in legend and in the sky to the constellation of the Serpent. If you have a dark sky, you might find this is one constellation that looks like what it’s supposed to be: a big guy holding a snake. The name Ophiuchus comes from two Greek words meaning serpent and holding.

Deep-sky objects in Ophiuchus

On a night when the moon is absent, take your binoculars and use them to scan Ophiuchus, which lies near the band of the Milky Way and so has many deep-sky wonders. Ophiuchus boasts of numerous globular clusters, for example. The two easiest globular clusters to see with ordinary binoculars are M10 and M12, as shown on the above chart. Through binoculars, they look like faint puffs of light, but with the telescope, you begin to see these globular clusters for what they really are. They are immense stellar cities spanning a hundred to a few hundred light-years in diameter, teeming with hundreds of thousands of stars.

Another big deep-sky favorite is the Pipe Nebula, a vast interstellar cloud of gas and dust sweeping across about 7 degrees of sky. At arm’s length, that’s about the width of three to four fingers. This dark nebula resides at a distance of 600 to 700 light-years in southern Ophiuchus. You can see it with the unaided eye in a dark, transparent sky. The Pipe Nebula is due east of the star Antares and due north of the stars Shaula and Lesath. These two stars (but not the Pipe Nebula) are shown on the above chart.

Ophiuchus in myth and star lore

In Greek sky lore, Ophiuchus represents Asclepius, Greek god of medicine and doctors. He is always holding a great serpent or snake. And, depending on how it’s used, a snake’s venom can either kill or cure. It’s said that Asclepius concocted a healing potion from the venom of Serpens the Serpent, mixing it with a Gorgon’s blood and an unknown herb. This potion gave humans access to immortality, until the god of the underworld, Pluto, appealed to the king of the gods. Pluto asked Zeus to reconsider the ramifications of the death of death.

We hardly know how Pluto made his appeal. Perhaps he said only that which never lives never dies, and that no mortal can have one without the other. Sophocles may have expressed the myth’s inherent message when saying:

Better to die, and sleep the never-waking sleep, than linger on and dare to live when the soul’s life is gone.

Possibly, the poet T.S. Eliot echoed the theme of the ever-living story in his Four Quartets:

We die with the dying:
See, they depart, and we go with them.
We are born with the dead:
See, they return, and bring us with them.

In any event, according to the myth, Zeus confiscated the potion, removed Asclepius from Earth and placed the gifted physician into the starry heavens. Today, the Staff of Asclepius – symbol of the World Health Organization and other medical organizations – pays tribute to this story and echoes the mighty celestial shape of the constellation Ophiuchus the Serpent Bearer.

Ophiuchus in history and science

It’s been more than 400 years since anyone has seen a supernova explosion of a star within our own Milky Way galaxy. But in the year 1604, a supernova known as Kepler’s Supernova exploded onto the scene, attaining unaided-eye visibility for 18 months. It shone in southern Ophiuchus, not all that far from the Pipe Nebula.

Kepler’s Supernova in 1604 came upon the heels of Tycho’s Supernova that lit up Cassiopeia in 1572. These supernovae sent shock waves into the intelligentsia of Europe, which firmly believed in the Aristotelian notion of an immutable universe outside the orbit of the moon. Tycho Brahe took a parallax measurement of the 1572 supernova, proving that it could not be an atmospheric phenomenon. In fact, the supernova shone well beyond the moon’s orbit. Shortly thereafter, Kepler’s Supernova in 1604 seemed to drive home the point all over again.

Moreover, Tycho Brahe measured the distance of a comet in 1577, also finding it to be farther away than the moon. Aristotelians wanted to believe comets were gases burning in the atmosphere, but once again, Tycho threw cold water on the idea of Aristotle’s immutable universe.

Bottom line: The sun lies within the boundaries of the constellation Ophiuchus the Serpent Bearer for about two weeks of every year. Thus, Ophiuchus is an unofficial member of the zodiac. Learn the difference between constellations and signs, and how to locate Ophiuchus.

The constellations of the zodiac

Say hello to Aries the Ram
Meet Taurus the Bull in the evening sky
Meet Gemini the Twins, home to 2 bright stars
Cancer the Crab and its Beehive Cluster
Leo the Lion and its backward question mark
Virgo the Maiden in northern spring skies
Meet Libra the Scales, a zodiacal constellation
Scorpius the Scorpion is a summertime delight
Sagittarius the Archer and its famous Teapot
Capricornus the Sea-goat has an arrowhead shape
Meet Aquarius the Water Bearer and its stars
Meet Pisces the Fish, 1st constellation of the zodiac

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If you’re in the Northern Hemisphere, look southward on your summer evenings for mighty Ophiuchus the Serpent Bearer. It’s surrounded by the constellations Serpens Cauda and Serpens Caput. Chart via EarthSky.

Ophiuchus, the unofficial 13th constellation of the zodiac

If you were born somewhere between November 30 and December 18, chances are the sun was in the constellation Ophiuchus the Serpent Bearer. Therefore, your “sign” should be Ophiuchus. But, of course, Ophiuchus is not an official constellation of the zodiac, nor will you find it in horoscopes. Ophiuchus the Serpent Bearer is a large constellation that you can spot near the southern horizon from the Northern Hemisphere during July, August and September evenings. The Serpent Bearer is standing on the Scorpion and its red star Antares.

From the Southern Hemisphere, Ophiuchus is closer to overhead. Ophiuchus’ brightest star is Rasalhague.

The official boundary lines for all 88 constellations were drawn up by the International Astronomical Union (IAU) in the 1930s.

Signs versus constellations

Poor Ophiuchus. Nobody ever claims him as a birth sign, despite the fact that the ecliptic runs across him, too. After all, the band of the zodiac extends some 8 degrees north and south of the ecliptic, spanning a total of 16 degrees in width. And the constellations are not evenly spaced along this band in our sky. The signs of the zodiac are familiar to all who read online astrology advice. There are 12 familiar signs of the zodiac, but no Ophiuchus.

Yet the moon and planets do regularly move within the boundaries of Ophiuchus. And so does the sun. The sun is in front of Ophiuchus from about November 30 to December 18 each year.

The sun is said to enter the sign Sagittarius around November 21, or whenever the sun is precisely 30 degrees west of the December solstice point. And then the sun then enters the sign Capricorn on the December 21 solstice. So the sun passes through the “sign” Sagittarius for the period before and up to the December solstice, irrespective of the fact that the sun is actually shining in front of the constellation Ophiuchus from November 30 to December 18.

By the way, the December solstice point moves one degree westward in front of the zodiacal constellations – or backdrop stars – in about 72 years. This means that the December solstice point will finally move into the constellation Ophiuchus by the year 2269.

Ophiuchus holding the serpent, Serpens, as depicted in Urania’s Mirror, a set of constellation cards published in London circa 1825. Image via Adam Cuerden/ Wikipedia.

When and where to locate Ophiuchus

The best time to observe Ophiuchus is during a Northern Hemisphere summer (Southern Hemisphere winter). From the Northern Hemisphere, late July and early August present this constellation high in the southern sky at nightfall and early evening. It’s in the southwest sky on autumn evenings in the Northern Hemisphere.

This rather large constellation fills the area of sky to the north of the constellation Scorpius the Scorpion and to the south of the constellation Hercules the Strongman. If you’re familiar with Scorpius’ brightest star Antares, try star-hopping to Ophiuchus from this ruddy gem of a star. The head of Ophiuchus is marked by the star Rasalhague (Alpha Ophiuchi).

View larger. | Ophiuchus the Serpent Bearer. Image via Wikipedia (CC BY 3.0).

Ophiuchus is joined in legend and in the sky to the constellation of the Serpent. If you have a dark sky, you might find this is one constellation that looks like what it’s supposed to be: a big guy holding a snake. The name Ophiuchus comes from two Greek words meaning serpent and holding.

Deep-sky objects in Ophiuchus

On a night when the moon is absent, take your binoculars and use them to scan Ophiuchus, which lies near the band of the Milky Way and so has many deep-sky wonders. Ophiuchus boasts of numerous globular clusters, for example. The two easiest globular clusters to see with ordinary binoculars are M10 and M12, as shown on the above chart. Through binoculars, they look like faint puffs of light, but with the telescope, you begin to see these globular clusters for what they really are. They are immense stellar cities spanning a hundred to a few hundred light-years in diameter, teeming with hundreds of thousands of stars.

Another big deep-sky favorite is the Pipe Nebula, a vast interstellar cloud of gas and dust sweeping across about 7 degrees of sky. At arm’s length, that’s about the width of three to four fingers. This dark nebula resides at a distance of 600 to 700 light-years in southern Ophiuchus. You can see it with the unaided eye in a dark, transparent sky. The Pipe Nebula is due east of the star Antares and due north of the stars Shaula and Lesath. These two stars (but not the Pipe Nebula) are shown on the above chart.

Ophiuchus in myth and star lore

In Greek sky lore, Ophiuchus represents Asclepius, Greek god of medicine and doctors. He is always holding a great serpent or snake. And, depending on how it’s used, a snake’s venom can either kill or cure. It’s said that Asclepius concocted a healing potion from the venom of Serpens the Serpent, mixing it with a Gorgon’s blood and an unknown herb. This potion gave humans access to immortality, until the god of the underworld, Pluto, appealed to the king of the gods. Pluto asked Zeus to reconsider the ramifications of the death of death.

We hardly know how Pluto made his appeal. Perhaps he said only that which never lives never dies, and that no mortal can have one without the other. Sophocles may have expressed the myth’s inherent message when saying:

Better to die, and sleep the never-waking sleep, than linger on and dare to live when the soul’s life is gone.

Possibly, the poet T.S. Eliot echoed the theme of the ever-living story in his Four Quartets:

We die with the dying:
See, they depart, and we go with them.
We are born with the dead:
See, they return, and bring us with them.

In any event, according to the myth, Zeus confiscated the potion, removed Asclepius from Earth and placed the gifted physician into the starry heavens. Today, the Staff of Asclepius – symbol of the World Health Organization and other medical organizations – pays tribute to this story and echoes the mighty celestial shape of the constellation Ophiuchus the Serpent Bearer.

Ophiuchus in history and science

It’s been more than 400 years since anyone has seen a supernova explosion of a star within our own Milky Way galaxy. But in the year 1604, a supernova known as Kepler’s Supernova exploded onto the scene, attaining unaided-eye visibility for 18 months. It shone in southern Ophiuchus, not all that far from the Pipe Nebula.

Kepler’s Supernova in 1604 came upon the heels of Tycho’s Supernova that lit up Cassiopeia in 1572. These supernovae sent shock waves into the intelligentsia of Europe, which firmly believed in the Aristotelian notion of an immutable universe outside the orbit of the moon. Tycho Brahe took a parallax measurement of the 1572 supernova, proving that it could not be an atmospheric phenomenon. In fact, the supernova shone well beyond the moon’s orbit. Shortly thereafter, Kepler’s Supernova in 1604 seemed to drive home the point all over again.

Moreover, Tycho Brahe measured the distance of a comet in 1577, also finding it to be farther away than the moon. Aristotelians wanted to believe comets were gases burning in the atmosphere, but once again, Tycho threw cold water on the idea of Aristotle’s immutable universe.

Bottom line: The sun lies within the boundaries of the constellation Ophiuchus the Serpent Bearer for about two weeks of every year. Thus, Ophiuchus is an unofficial member of the zodiac. Learn the difference between constellations and signs, and how to locate Ophiuchus.

The constellations of the zodiac

Say hello to Aries the Ram
Meet Taurus the Bull in the evening sky
Meet Gemini the Twins, home to 2 bright stars
Cancer the Crab and its Beehive Cluster
Leo the Lion and its backward question mark
Virgo the Maiden in northern spring skies
Meet Libra the Scales, a zodiacal constellation
Scorpius the Scorpion is a summertime delight
Sagittarius the Archer and its famous Teapot
Capricornus the Sea-goat has an arrowhead shape
Meet Aquarius the Water Bearer and its stars
Meet Pisces the Fish, 1st constellation of the zodiac

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A moon for Mars! Asaph Hall finds Phobos 149 years ago

Asaph Hall discovered Phobos, a moon for Mars, on August 17, 1877. This image of the large crater Stickney on the Martian moon Phobos is color-enhanced. The crater is 5.6 miles (9 km) in diameter, so it covers a substantial proportion of Phobos’ surface. The impact almost destroyed the small moon! Notice the smaller crater within Stickney, about 1.2 miles (2 km) in diameter, resulting from a later impact. Image via HiRISE/ MRO/ LPL (U. Arizona)/ NASA.

August 17, 1877: Asaph Hall discovers a moon for Mars

On August 17 149 years ago, American astronomer Asaph Hall discovered the first known moon for our neighboring planet, Mars. Later that year, he found a second Martian moon. Today, we call the first and larger moon Phobos. And we call the second and smaller one Deimos.

To date, Phobos and Deimos remain the only known moons of Mars.

Both Phobos and Deimos are potato-shaped. They look more like asteroids than like Earth’s much-larger companion moon. In fact, it’s likely that Mars captured these little worlds that now orbit the red planet. Studies have indicated that – millions of years from now – Phobos will shatter and form a ring around Mars. Some astronomers think Phobos alternates between being a planetary ring, then clumping up again to form a moon. More about ring theories of Phobos below.

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Phobos and Deimos, fear and terror

The names Phobos and Deimos mean fear and terror, respectively. Their names refer to the sons of the war god Ares in Greek mythology. Ares was the Greek counterpart to the Roman war god Mars.

Although it’s the larger of Mars’ two moons, Phobos is tiny. It has a mean diameter of only about 14 miles (22.5 km). But it’s seven times more massive than Deimos, which has a mean diameter of about 7.7 miles (12.4 km). For these moons, we’re speaking in terms of a mean diameter because both moons are oblong in shape and not spherical. In contrast, Earth’s moon is nearly round, since it’s large enough for its gravity to have pulled it into a spherical shape.

Earth’s moon is also much larger (2,159 miles or 3,475 km in diameter). Since both Phobos and Deimos are so tiny, they have very weak gravity. And that means they don’t have enough gravity to make them round.

Mariner 9 was 1st to see them close

During Mariner 9’s mission to Mars in 1971 and 1972, scientists got their first closeup look at Phobos. Just like asteroids, its oblong surface shows many small craters. But one large crater stood out as much bigger than the rest. Astronomers named it Stickney Crater, for Angeline Stickney: an American academic, suffragist and mathematician, and Asaph Hall’s wife.

Stickney looks like a giant hole on one end of Phobos. Whatever rocky body created it was almost big enough to have shattered the moon. It’s thought that, whenever the impact occurred, Phobos barely survived.

Viking I image of Phobos and its large crater Stickney. The spacecraft captured this image in June 1977, 100 years after the discovery of Phobos. Image via NASA/ ESA.

A closer view of the grooves on Phobos. Image via NASA/ JPL-Caltech/ University of Arizona.

The Viking orbiter obtained this global map of Phobos. Image via NASA/ Astrogeology Science Center/ Planetary Data System/ Phil Stooke.

Was Phobos once a ring? Will it be again?

Phobos has long, shallow grooves running across its surface, radiating away from Stickney. Many planetary scientists believe these grooves are early signs of eventual structural failure in the moon. They say it’s possible that – some 50 million years from now – Phobos will break apart, forming a ring around Mars.

A study in 2018 suggested that rolling boulders created the grooves, spraying across the surface during impact. As Ken Ramsley, a planetary science researcher at Brown University who led the work, explained:

These grooves are a distinctive feature of Phobos, and planetary scientists have been debating how they formed for 40 years. We think this study is another step toward zeroing in on an explanation.

More ring theories

In 2017, a new theory by Purdue University scientists suggested Phobos might not only break apart and form a ring around the planet but also suggests this ring formation happened before.

David Minton, a professor, and Andrew Hesselbrock, a doctoral student, both at Purdue, developed a computer model showing debris ejected into space from an asteroid or other body slamming into Mars. This event – some 4.3 billion years ago – would cause the material to subsequently alternate between becoming a planetary ring and clumping up again to form the moon Phobos.

Size and visual comparison of Phobos (left) and Deimos (right). Image via NASA.

Daily Owl #Fact

One day #Mars will have a ring around it?

In the next 20-40 million years Mars’ largest moon Phobos will be torn apart by gravitational forces leading to the creation of a ring that could last up to 100 million years#NFTs #Moon #Space pic.twitter.com/IIYHCkgDhf

— MarsBirds? (@mars_birds) July 12, 2022

Deimos played a role

Another study, from scientists at Purdue and the SETI Institute in June 2020, also concluded that Mars used to have a ring or series of rings. The scientists based that study on an analysis of the orbit of the other Martian moon, Deimos.

Deimos is smaller than Phobos. And it has an orbit that’s tilted with respect to Mars’ equator by about 2 degrees. Meanwhile, Phobos’ orbit isn’t inclined as much. The larger moon is inclined to Mars’ equator by only about 1 degree. The scientists said in a statement:

These orbital resonances are picky but predictable … We can tell that only an outward-moving moon could have strongly affected Deimos, which means that Mars must have had a ring pushing the inner moon outward … This moon may have been 20 times as massive as Phobos, and may have been its ‘grandparent’ existing just over 3 billion years ago … [It] was followed by two more ring-moon cycles, with the latest moon being Phobos.

So, basically, there may have been a moon about 20 times more massive than Phobos, and Mars’ rings pushed it outward. And at least two times since then, that moon broke apart and then formed a new ring, before the material coalesced together again to form a new moon. Phobos is now that current moon. The scientists say it will eventually break apart to form a new ring, thus continuing the cycle.

Scientists also now know Phobos is much younger than Deimos – perhaps only 200 million years old – which would fit the moon/ring scenario. The Phobos we see today is simply a newer and smaller version of its original self.

Eclipsing moons

Asaph Hall probably never imagined the idea of Phobos breaking apart and forming a ring around Mars. And he couldn’t possibly have imagined the video below, which was acquired by NASA’s Mars rover Curiosity on August 1, 2013. This video shows both moons, Phobos and Deimos, as you might see them while standing on the surface of Mars. You can clearly see some of the large craters on Phobos in these images.

This was the first time that images taken from Mars’ surface caught one moon eclipsing the other … but probably not the last.

Bottom line: On this date in 1877, American astronomer Asaph Hall discovered a moon for Mars: Phobos, the larger of Mars’ two moons. He discovered the other moon, Deimos, later that year.

Read more: Watch as Mars’ moons trade places in the sky

Read more: New Mars and Deimos pics from revealing Hera flyby

The post A moon for Mars! Asaph Hall finds Phobos 149 years ago first appeared on EarthSky.

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Asaph Hall discovered Phobos, a moon for Mars, on August 17, 1877. This image of the large crater Stickney on the Martian moon Phobos is color-enhanced. The crater is 5.6 miles (9 km) in diameter, so it covers a substantial proportion of Phobos’ surface. The impact almost destroyed the small moon! Notice the smaller crater within Stickney, about 1.2 miles (2 km) in diameter, resulting from a later impact. Image via HiRISE/ MRO/ LPL (U. Arizona)/ NASA.

August 17, 1877: Asaph Hall discovers a moon for Mars

On August 17 149 years ago, American astronomer Asaph Hall discovered the first known moon for our neighboring planet, Mars. Later that year, he found a second Martian moon. Today, we call the first and larger moon Phobos. And we call the second and smaller one Deimos.

To date, Phobos and Deimos remain the only known moons of Mars.

Both Phobos and Deimos are potato-shaped. They look more like asteroids than like Earth’s much-larger companion moon. In fact, it’s likely that Mars captured these little worlds that now orbit the red planet. Studies have indicated that – millions of years from now – Phobos will shatter and form a ring around Mars. Some astronomers think Phobos alternates between being a planetary ring, then clumping up again to form a moon. More about ring theories of Phobos below.

Catch the wonder of the night sky. Subscribe to EarthSky’s free daily newsletter for science, stars, planets and more.

Phobos and Deimos, fear and terror

The names Phobos and Deimos mean fear and terror, respectively. Their names refer to the sons of the war god Ares in Greek mythology. Ares was the Greek counterpart to the Roman war god Mars.

Although it’s the larger of Mars’ two moons, Phobos is tiny. It has a mean diameter of only about 14 miles (22.5 km). But it’s seven times more massive than Deimos, which has a mean diameter of about 7.7 miles (12.4 km). For these moons, we’re speaking in terms of a mean diameter because both moons are oblong in shape and not spherical. In contrast, Earth’s moon is nearly round, since it’s large enough for its gravity to have pulled it into a spherical shape.

Earth’s moon is also much larger (2,159 miles or 3,475 km in diameter). Since both Phobos and Deimos are so tiny, they have very weak gravity. And that means they don’t have enough gravity to make them round.

Mariner 9 was 1st to see them close

During Mariner 9’s mission to Mars in 1971 and 1972, scientists got their first closeup look at Phobos. Just like asteroids, its oblong surface shows many small craters. But one large crater stood out as much bigger than the rest. Astronomers named it Stickney Crater, for Angeline Stickney: an American academic, suffragist and mathematician, and Asaph Hall’s wife.

Stickney looks like a giant hole on one end of Phobos. Whatever rocky body created it was almost big enough to have shattered the moon. It’s thought that, whenever the impact occurred, Phobos barely survived.

Viking I image of Phobos and its large crater Stickney. The spacecraft captured this image in June 1977, 100 years after the discovery of Phobos. Image via NASA/ ESA.

A closer view of the grooves on Phobos. Image via NASA/ JPL-Caltech/ University of Arizona.

The Viking orbiter obtained this global map of Phobos. Image via NASA/ Astrogeology Science Center/ Planetary Data System/ Phil Stooke.

Was Phobos once a ring? Will it be again?

Phobos has long, shallow grooves running across its surface, radiating away from Stickney. Many planetary scientists believe these grooves are early signs of eventual structural failure in the moon. They say it’s possible that – some 50 million years from now – Phobos will break apart, forming a ring around Mars.

A study in 2018 suggested that rolling boulders created the grooves, spraying across the surface during impact. As Ken Ramsley, a planetary science researcher at Brown University who led the work, explained:

These grooves are a distinctive feature of Phobos, and planetary scientists have been debating how they formed for 40 years. We think this study is another step toward zeroing in on an explanation.

More ring theories

In 2017, a new theory by Purdue University scientists suggested Phobos might not only break apart and form a ring around the planet but also suggests this ring formation happened before.

David Minton, a professor, and Andrew Hesselbrock, a doctoral student, both at Purdue, developed a computer model showing debris ejected into space from an asteroid or other body slamming into Mars. This event – some 4.3 billion years ago – would cause the material to subsequently alternate between becoming a planetary ring and clumping up again to form the moon Phobos.

Size and visual comparison of Phobos (left) and Deimos (right). Image via NASA.

Daily Owl #Fact

One day #Mars will have a ring around it?

In the next 20-40 million years Mars’ largest moon Phobos will be torn apart by gravitational forces leading to the creation of a ring that could last up to 100 million years#NFTs #Moon #Space pic.twitter.com/IIYHCkgDhf

— MarsBirds? (@mars_birds) July 12, 2022

Deimos played a role

Another study, from scientists at Purdue and the SETI Institute in June 2020, also concluded that Mars used to have a ring or series of rings. The scientists based that study on an analysis of the orbit of the other Martian moon, Deimos.

Deimos is smaller than Phobos. And it has an orbit that’s tilted with respect to Mars’ equator by about 2 degrees. Meanwhile, Phobos’ orbit isn’t inclined as much. The larger moon is inclined to Mars’ equator by only about 1 degree. The scientists said in a statement:

These orbital resonances are picky but predictable … We can tell that only an outward-moving moon could have strongly affected Deimos, which means that Mars must have had a ring pushing the inner moon outward … This moon may have been 20 times as massive as Phobos, and may have been its ‘grandparent’ existing just over 3 billion years ago … [It] was followed by two more ring-moon cycles, with the latest moon being Phobos.

So, basically, there may have been a moon about 20 times more massive than Phobos, and Mars’ rings pushed it outward. And at least two times since then, that moon broke apart and then formed a new ring, before the material coalesced together again to form a new moon. Phobos is now that current moon. The scientists say it will eventually break apart to form a new ring, thus continuing the cycle.

Scientists also now know Phobos is much younger than Deimos – perhaps only 200 million years old – which would fit the moon/ring scenario. The Phobos we see today is simply a newer and smaller version of its original self.

Eclipsing moons

Asaph Hall probably never imagined the idea of Phobos breaking apart and forming a ring around Mars. And he couldn’t possibly have imagined the video below, which was acquired by NASA’s Mars rover Curiosity on August 1, 2013. This video shows both moons, Phobos and Deimos, as you might see them while standing on the surface of Mars. You can clearly see some of the large craters on Phobos in these images.

This was the first time that images taken from Mars’ surface caught one moon eclipsing the other … but probably not the last.

Bottom line: On this date in 1877, American astronomer Asaph Hall discovered a moon for Mars: Phobos, the larger of Mars’ two moons. He discovered the other moon, Deimos, later that year.

Read more: Watch as Mars’ moons trade places in the sky

Read more: New Mars and Deimos pics from revealing Hera flyby

The post A moon for Mars! Asaph Hall finds Phobos 149 years ago first appeared on EarthSky.

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Swift spacecraft, and a mission to save it, caught on video

The Sociedad de Astronomía del Caribe in Añasco, Puerto Rico, captured this video at about 8:02–8:03 p.m. AST on August 10, 2026. It shows an experimental commercial robotic repair vehicle called LINK, slightly ahead of NASA’s Swift spacecraft in low Earth orbit (by about a minute). Both LINK and Swift now appear to have the same (or a similar) trajectory, which is good news. LINK is meant to boost Swift to a higher orbit, saving it from falling back into Earth’s atmosphere by the end of 2026.

The nail-biting Swift spacecraft rescue effort

The Neil Gehrels Swift Observatory, better known as Swift, has been orbiting Earth since 2004. It has been studying the most powerful explosions in the universe: gamma-ray bursts. Now, Swift’s orbit is rapidly decaying. That means Swift is slowly falling back to Earth.

And if nothing stops it, it will burn up in Earth’s atmosphere later this year. If that happens, Swift is expected to put on a spectacular, fiery show.

But something might save it. In an effort to extend the life of this important science mission, NASA has employed a 2nd spacecraft – a commercial robotic repair vehicle called LINK, built by Katalyst Space – on July 3, 2026.

So LINK was supposed to chase down Swift, grab it, and raise its orbit. But about three weeks into the mission, two of LINK’s three reaction wheels failed, sending LINK into an uncontrolled spin and causing communication to be intermittent. What will happen now? Is there any good news? As it turns out … there is.

The current status of the rescue

NASA said on August 11 in its Swift blog that a flight software update has now been uploaded to LINK. NASA said:

The software update’s new attitude control algorithms are designed to maintain LINK’s stability using the spacecraft’s remaining actuators.

And, in recent days, LINK does appear more stable. Amateur astronomers in Puerto Rico – with the Sociedad de Astronomía del Caribe – captured video of both LINK and Swift in the same (or a similar) orbit around Earth. The video comes from Añasco, Puerto Rico, at about 8:02–8:03 p.m. AST on August 10, 2026. Watch the video at the top of this post. And keep reading to learn more.

In the meantime, be aware that there’s a real clock ticking here. Swift is gradually losing altitude because of atmospheric drag. If it drops below roughly 300 km (186 miles), recovery becomes essentially impossible; NASA expects that point to arrive around October.

Meet the space-based Swift Observatory. Its orbit is decaying; it is falling back to Earth. NASA plans to save it, and boost it to a higher orbit, with a rescue mission called LINK. If there’s no intervention, Swift will plunge back to Earth by the fall of 2026. Image via NASA.

Seeing Swift and LINK in orbit

Amateur astronomers frequently try to spy faint spacecraft in orbit around Earth, and LINK and Swift are no exceptions. The website Heavens-Above.com is designed specifically to enable observers to become aware of satellite passes from their location.

The Sociedad de Astronomia del Caribe in Añasco, Puerto Rico, caught both Swift and LINK on video on August 2, 2026. That earlier video showed that Link was about 8 minutes behind the Swift spacecraft.

But, between August 9 and 10, the club’s cameras showed LINK as slightly ahead of Swift in orbit. That’s what you’ll see if you watch the video above.

In the Sociedad de Astronomia del Caribe video at the top of this post, the Link rescue spacecraft passes very close to a bright star. The star is Antares, brightest light in the constellation Scorpius the Scorpion. A minute later, the Swift Observatory is seen also passing by this bright star.

The video capture was possible by analyzing the trajectory of both spacecraft using various sources including Heavens-Above.com.

It’s encouraging that LINK and Swift are so close together! And that they seem to be following the same (or a similar) path.

Don’t miss the next unmissable sky event! Subscribe to EarthSky’s free daily newsletter for sky and science news.

Can you see LINK and Swift?

Observers can try to glimpse the decaying Swift Observatory with the eye. It sometimes reaches a visual magnitude around +2.0 to +1.5, making it as bright as a moderately bright star.

It would be especially easy to spot if you were observing far from city lights, once you know where to look.

The Link rescue spacecraft is fainter and more difficult to see. But some experienced observers have reported seeing it with the unaided eye.

To spot the Swift Observatory or the LINK rescue vehicle in orbit using the website Heavens-Above.com, you need custom visibility predictions for your exact location.  

Here’s how to set your observing location:

• Navigate to the Heavens-Above main site or open the Heavens-Above mobile app.
• Click on Configuration (or the location selector in the upper-right corner).
• Input your specific city or exact GPS coordinates so that pass times and trajectory angles calculate accurately for your horizon.

Here’s how to find the 2 spacecraft:

• Return to the main database menu and locate the Satellites section.
• Select Search database for satellite (or use the Satellite database / Search link).
• Query for Swift (the Neil Gehrels Swift Observatory, NORAD ID 28485) or LINK (or Katalyst Space / Pegasus XL payload related to the mission).

Here’s how to generate the pass predictions:

• Open the satellite’s details page and click 10-day predictions for visible passes (or change filters to show “All passes” if you want daytime/radio passes).  
• Review the pass table for key metrics. These are: start / highest / end times; altitude aka elevation (look for passes exceeding 30 to 40 degrees elevation for clear viewing above trees or buildings); and brightness aka magnitude (lower or negative numbers indicate brighter objects, and Swift typically reaches a visual magnitude of around +1.5 to +2.0, making it visible to the unaided eye under dark sky conditions.)

Here’s how to use the interactive sky charts

• Click on any specific date/pass row to generate a star chart.
• The chart overlays the satellite’s precise trajectory against recognizable constellations and stars (such as Scorpius or Antares), showing you exactly where to aim your eyes, binoculars, or camera equipment.

This video walk-through shows how to set up your ground coordinates and fetch pass predictions on Heavens-Above: How to Track the ISS with Heavens-Above.com.

Engineers from Katalyst Space test the LINK spacecraft that will launch to save Swift. Image via Scott Wiessinger/ NASA.

Boost timeline

Below is a timeline from launch through the boost steps until Swift returns to science operations. NASA has temporarily suspended science operations on Swift until the boosting mission is complete.

According to NASA’s timeline, it will take several months to complete the boost of the Swift spacecraft. This artist’s concept shows Swift at top and LINK below. Image via Katalyst Space/ NASA/ Goddard Space Flight Center.

More about the Swift spacecraft

The Swift spacecraft has three telescopes that watch the night sky. They are the Burst Alert Telescope, X-Ray Telescope and Ultraviolet/Optical Telescope.

The Burst Alert Telescope (BAT) is Swift’s wide-field gamma-ray detector. This telescope continuously monitors a large portion of the sky, watching for sudden flashes of high-energy gamma rays from gamma-ray bursts. When it detects a burst, it quickly calculates the object’s position and sends the coordinates to astronomers worldwide. It also directs the Swift spacecraft to rapidly turn toward the event for closer study.

Once Swift has slewed toward a newly detected gamma-ray burst, the X-Ray Telescope (XRT) takes over. It observes the burst’s fading X-ray afterglow. And it measures how its brightness changes over time and analyzes the energies of the emitted X-rays. Also, the XRT can pinpoint a burst’s location better than BAT and can continue tracking the event for days or even weeks. So the XRT helps scientists understand the physics of these powerful explosions and their environments.

Finally, the Ultraviolet/Optical Telescope studies gamma-ray bursts and other cosmic objects in ultraviolet and visible light. It provides Swift’s most precise positions for newly discovered bursts. It also captures details about their brightness, color and evolution. Overall, these observations help astronomers determine distances, identify host galaxies and better understand the nature of the explosions and other transient events Swift observes across the universe.

Bottom line: The Swift space telescope is falling back to Earth. The LINK spacecraft is trying to save it. See both in orbit in a new video.

Via NASA

Read more: What is the Earth’s most distant spacecraft?

Read more: Remember when DART struck an asteroid? New surprises!

The post Swift spacecraft, and a mission to save it, caught on video first appeared on EarthSky.

from EarthSky https://ift.tt/ltTPyOa

The Sociedad de Astronomía del Caribe in Añasco, Puerto Rico, captured this video at about 8:02–8:03 p.m. AST on August 10, 2026. It shows an experimental commercial robotic repair vehicle called LINK, slightly ahead of NASA’s Swift spacecraft in low Earth orbit (by about a minute). Both LINK and Swift now appear to have the same (or a similar) trajectory, which is good news. LINK is meant to boost Swift to a higher orbit, saving it from falling back into Earth’s atmosphere by the end of 2026.

The nail-biting Swift spacecraft rescue effort

The Neil Gehrels Swift Observatory, better known as Swift, has been orbiting Earth since 2004. It has been studying the most powerful explosions in the universe: gamma-ray bursts. Now, Swift’s orbit is rapidly decaying. That means Swift is slowly falling back to Earth.

And if nothing stops it, it will burn up in Earth’s atmosphere later this year. If that happens, Swift is expected to put on a spectacular, fiery show.

But something might save it. In an effort to extend the life of this important science mission, NASA has employed a 2nd spacecraft – a commercial robotic repair vehicle called LINK, built by Katalyst Space – on July 3, 2026.

So LINK was supposed to chase down Swift, grab it, and raise its orbit. But about three weeks into the mission, two of LINK’s three reaction wheels failed, sending LINK into an uncontrolled spin and causing communication to be intermittent. What will happen now? Is there any good news? As it turns out … there is.

The current status of the rescue

NASA said on August 11 in its Swift blog that a flight software update has now been uploaded to LINK. NASA said:

The software update’s new attitude control algorithms are designed to maintain LINK’s stability using the spacecraft’s remaining actuators.

And, in recent days, LINK does appear more stable. Amateur astronomers in Puerto Rico – with the Sociedad de Astronomía del Caribe – captured video of both LINK and Swift in the same (or a similar) orbit around Earth. The video comes from Añasco, Puerto Rico, at about 8:02–8:03 p.m. AST on August 10, 2026. Watch the video at the top of this post. And keep reading to learn more.

In the meantime, be aware that there’s a real clock ticking here. Swift is gradually losing altitude because of atmospheric drag. If it drops below roughly 300 km (186 miles), recovery becomes essentially impossible; NASA expects that point to arrive around October.

Meet the space-based Swift Observatory. Its orbit is decaying; it is falling back to Earth. NASA plans to save it, and boost it to a higher orbit, with a rescue mission called LINK. If there’s no intervention, Swift will plunge back to Earth by the fall of 2026. Image via NASA.

Seeing Swift and LINK in orbit

Amateur astronomers frequently try to spy faint spacecraft in orbit around Earth, and LINK and Swift are no exceptions. The website Heavens-Above.com is designed specifically to enable observers to become aware of satellite passes from their location.

The Sociedad de Astronomia del Caribe in Añasco, Puerto Rico, caught both Swift and LINK on video on August 2, 2026. That earlier video showed that Link was about 8 minutes behind the Swift spacecraft.

But, between August 9 and 10, the club’s cameras showed LINK as slightly ahead of Swift in orbit. That’s what you’ll see if you watch the video above.

In the Sociedad de Astronomia del Caribe video at the top of this post, the Link rescue spacecraft passes very close to a bright star. The star is Antares, brightest light in the constellation Scorpius the Scorpion. A minute later, the Swift Observatory is seen also passing by this bright star.

The video capture was possible by analyzing the trajectory of both spacecraft using various sources including Heavens-Above.com.

It’s encouraging that LINK and Swift are so close together! And that they seem to be following the same (or a similar) path.

Don’t miss the next unmissable sky event! Subscribe to EarthSky’s free daily newsletter for sky and science news.

Can you see LINK and Swift?

Observers can try to glimpse the decaying Swift Observatory with the eye. It sometimes reaches a visual magnitude around +2.0 to +1.5, making it as bright as a moderately bright star.

It would be especially easy to spot if you were observing far from city lights, once you know where to look.

The Link rescue spacecraft is fainter and more difficult to see. But some experienced observers have reported seeing it with the unaided eye.

To spot the Swift Observatory or the LINK rescue vehicle in orbit using the website Heavens-Above.com, you need custom visibility predictions for your exact location.  

Here’s how to set your observing location:

• Navigate to the Heavens-Above main site or open the Heavens-Above mobile app.
• Click on Configuration (or the location selector in the upper-right corner).
• Input your specific city or exact GPS coordinates so that pass times and trajectory angles calculate accurately for your horizon.

Here’s how to find the 2 spacecraft:

• Return to the main database menu and locate the Satellites section.
• Select Search database for satellite (or use the Satellite database / Search link).
• Query for Swift (the Neil Gehrels Swift Observatory, NORAD ID 28485) or LINK (or Katalyst Space / Pegasus XL payload related to the mission).

Here’s how to generate the pass predictions:

• Open the satellite’s details page and click 10-day predictions for visible passes (or change filters to show “All passes” if you want daytime/radio passes).  
• Review the pass table for key metrics. These are: start / highest / end times; altitude aka elevation (look for passes exceeding 30 to 40 degrees elevation for clear viewing above trees or buildings); and brightness aka magnitude (lower or negative numbers indicate brighter objects, and Swift typically reaches a visual magnitude of around +1.5 to +2.0, making it visible to the unaided eye under dark sky conditions.)

Here’s how to use the interactive sky charts

• Click on any specific date/pass row to generate a star chart.
• The chart overlays the satellite’s precise trajectory against recognizable constellations and stars (such as Scorpius or Antares), showing you exactly where to aim your eyes, binoculars, or camera equipment.

This video walk-through shows how to set up your ground coordinates and fetch pass predictions on Heavens-Above: How to Track the ISS with Heavens-Above.com.

Engineers from Katalyst Space test the LINK spacecraft that will launch to save Swift. Image via Scott Wiessinger/ NASA.

Boost timeline

Below is a timeline from launch through the boost steps until Swift returns to science operations. NASA has temporarily suspended science operations on Swift until the boosting mission is complete.

According to NASA’s timeline, it will take several months to complete the boost of the Swift spacecraft. This artist’s concept shows Swift at top and LINK below. Image via Katalyst Space/ NASA/ Goddard Space Flight Center.

More about the Swift spacecraft

The Swift spacecraft has three telescopes that watch the night sky. They are the Burst Alert Telescope, X-Ray Telescope and Ultraviolet/Optical Telescope.

The Burst Alert Telescope (BAT) is Swift’s wide-field gamma-ray detector. This telescope continuously monitors a large portion of the sky, watching for sudden flashes of high-energy gamma rays from gamma-ray bursts. When it detects a burst, it quickly calculates the object’s position and sends the coordinates to astronomers worldwide. It also directs the Swift spacecraft to rapidly turn toward the event for closer study.

Once Swift has slewed toward a newly detected gamma-ray burst, the X-Ray Telescope (XRT) takes over. It observes the burst’s fading X-ray afterglow. And it measures how its brightness changes over time and analyzes the energies of the emitted X-rays. Also, the XRT can pinpoint a burst’s location better than BAT and can continue tracking the event for days or even weeks. So the XRT helps scientists understand the physics of these powerful explosions and their environments.

Finally, the Ultraviolet/Optical Telescope studies gamma-ray bursts and other cosmic objects in ultraviolet and visible light. It provides Swift’s most precise positions for newly discovered bursts. It also captures details about their brightness, color and evolution. Overall, these observations help astronomers determine distances, identify host galaxies and better understand the nature of the explosions and other transient events Swift observes across the universe.

Bottom line: The Swift space telescope is falling back to Earth. The LINK spacecraft is trying to save it. See both in orbit in a new video.

Via NASA

Read more: What is the Earth’s most distant spacecraft?

Read more: Remember when DART struck an asteroid? New surprises!

The post Swift spacecraft, and a mission to save it, caught on video first appeared on EarthSky.

from EarthSky https://ift.tt/ltTPyOa

Deep partial lunar eclipse of the August 27-28 Sturgeon Moon

Here’s a global map showing where the August 27-28, 2026, partial lunar eclipse is visible. Image via thesuntoday.org.

The crest of the August full Sturgeon Moon falls at 4:18 UTC on August 28 (11:18 p.m. CDT on August 27).

And people in Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean will see a deep partial lunar eclipse overnight on August 27-28, 2026.

The whole half of Earth facing the full moon – that is, the whole half of Earth that’s in nighttime – will see the lunar eclipse. It’s well placed for the Western Hemisphere. Of course, lunar eclipses are safe to view with the unaided eye. Binoculars and telescopes aren’t required to view a lunar eclipse, but they do enhance the view.

At maximum eclipse, about 96% of the moon will enter Earth’s dark umbral shadow. For the most part, the August 27-28, 2026, lunar eclipse will appear nearly as a total lunar eclipse of the moon. In other words, as the eclipse progresses and is near maximum eclipse, you should notice the red glow of totality and a bright white patch along the moon’s northeastern limb.

Check timeanddate.com for precise timing from your location.

Chart showing the stages of the August 28, 2026, partial lunar eclipse. The maximum eclipse is at 04:13 UTC on August 28. Image via thesuntoday.org.

When the lunar eclipse occurs worldwide

Penumbral eclipse begins at 1:23 UTC on August 28, 2026. That’s 8:23 p.m. CDT on August 27. Earth’s lighter penumbral shadow will begin crossing the moon’s face. You probably won’t notice it at first. But, as the eclipse progresses, you should see a subtle shading on the moon.
Partial eclipse begins at 2:33 UTC on August 28, 2026. That’s 9:33 p.m. CDT on August 27. As the partial eclipse begins, it’ll appear as if a tiny, but dark, bite is taken from one edge of the moon.
Greatest eclipse at 4:12 UTC on August 28, 2026. That’s 11:12 p.m. CDT on August 27. At maximum eclipse, about 96% of the moon’s disk will lie inside Earth’s dark umbral shadow.
Partial eclipse ends at 5:52 UTC on August 28, 2026. That’s 12:52 a.m. CDT.
Penumbral eclipse ends at 7:02 UTC on August 28, 2026. That’s 2:02 a.m. CDT.

Source: Eclipsewise.com

View at EarthSky Community Photos. | Robert Hall in South Mississippi took this image of the lunar eclipse on November 19, 2021. He wrote: “The moon turned red once it was 90% eclipsed.” Thank you, Robert! See more lunar eclipse photos below.

Visit timeanddate.com to get an exact timing of the eclipse from your location.

Animated map of the lunar eclipse.

How long will it last?

From start to finish, the eclipse will last 339 minutes. And the moon will be in Earth’s dark shadow – for the partial eclipse – for 199 minutes.

Read more: Why no eclipse at every full and new moon?

During a lunar eclipse, Earth’s shadow falls on the moon. So if the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. But if the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via timeanddate.com. Used with permission.

Moon and Soros

The moment of greatest eclipse takes place 5.8 days after the moon reaches apogee, its farthest point from Earth for the month.

The Saros catalog describes the periodicity of eclipses. This August 27-28 total lunar eclipse belongs to Saros 138. It is number 29 of 82 lunar eclipses in the series. All eclipses in this series occur at the moon’s ascending node. The moon moves southward with respect to the node with each succeeding eclipse in the series.

The instant of greatest eclipse – when the axis of the moon’s shadow cone passes closest to Earth’s center – takes place at 4:12 UTC on August 28. The moon will lie at zenith – directly overhead – at a point in the Brazilian Amazon.

Who can see lunar eclipses?

A full moon is up only at night. And a total lunar eclipse is visible from all parts of Earth that are experiencing night while the eclipse is taking place. But some will see the eclipse more clearly, or more thoroughly, than others, depending on location. For example, some will see it at moonrise or moonset, when the moon is low in the sky.

View at EarthSky Community Photos. | Atharva Maurya captured this image on March 3, 2026, from India and wrote: “This image showcases the different phases of lunar eclipse of March 3, 2026.” Thank you, Atharva!

The constellation behind the partial lunar eclipse

The August 28, 2026, partial lunar eclipse occurs when the moon is in the constellation of Aquarius the Water Bearer.

Find the moon’s path with respect to Earth’s umbral and penumbral shadows below.

A map for the partial lunar eclipse on August 27-28, 2026. It sweeps across Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean. Areas in white on the map will see all of the partial eclipse. The line down the middle notes where the greatest eclipse occurs. Shaded areas will see part of the eclipse and dark areas are where the eclipse is not visible. Note the difference between UTC and TD (terrestrial dynamical time, often abbreviated TT as well). Key to lunar eclipse maps here. Image via Fred Espenak/ EclipseWise. Used with permission.

Maps and data for the total lunar eclipse

• Detailed lunar eclipse figure
• Visual Appearance of Lunar Eclipses
• Danjon Scale of Lunar Eclipse Brightness
• August 28, 2028, eclipse map animation

More resources

See Spectacular total lunar eclipse images from March 2-3, 2026

How to photograph a lunar eclipse

Submit your lunar eclipse photo to EarthSky here.

EarthSky’s monthly night sky guide: Visible planets and more

Bottom line: A deep partial lunar eclipse takes place on August 27-28, 2026, visible in Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean. Maps and details here.

The post Deep partial lunar eclipse of the August 27-28 Sturgeon Moon first appeared on EarthSky.

from EarthSky https://ift.tt/JQaG5Hm

Here’s a global map showing where the August 27-28, 2026, partial lunar eclipse is visible. Image via thesuntoday.org.

The crest of the August full Sturgeon Moon falls at 4:18 UTC on August 28 (11:18 p.m. CDT on August 27).

And people in Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean will see a deep partial lunar eclipse overnight on August 27-28, 2026.

The whole half of Earth facing the full moon – that is, the whole half of Earth that’s in nighttime – will see the lunar eclipse. It’s well placed for the Western Hemisphere. Of course, lunar eclipses are safe to view with the unaided eye. Binoculars and telescopes aren’t required to view a lunar eclipse, but they do enhance the view.

At maximum eclipse, about 96% of the moon will enter Earth’s dark umbral shadow. For the most part, the August 27-28, 2026, lunar eclipse will appear nearly as a total lunar eclipse of the moon. In other words, as the eclipse progresses and is near maximum eclipse, you should notice the red glow of totality and a bright white patch along the moon’s northeastern limb.

Check timeanddate.com for precise timing from your location.

Chart showing the stages of the August 28, 2026, partial lunar eclipse. The maximum eclipse is at 04:13 UTC on August 28. Image via thesuntoday.org.

When the lunar eclipse occurs worldwide

Penumbral eclipse begins at 1:23 UTC on August 28, 2026. That’s 8:23 p.m. CDT on August 27. Earth’s lighter penumbral shadow will begin crossing the moon’s face. You probably won’t notice it at first. But, as the eclipse progresses, you should see a subtle shading on the moon.
Partial eclipse begins at 2:33 UTC on August 28, 2026. That’s 9:33 p.m. CDT on August 27. As the partial eclipse begins, it’ll appear as if a tiny, but dark, bite is taken from one edge of the moon.
Greatest eclipse at 4:12 UTC on August 28, 2026. That’s 11:12 p.m. CDT on August 27. At maximum eclipse, about 96% of the moon’s disk will lie inside Earth’s dark umbral shadow.
Partial eclipse ends at 5:52 UTC on August 28, 2026. That’s 12:52 a.m. CDT.
Penumbral eclipse ends at 7:02 UTC on August 28, 2026. That’s 2:02 a.m. CDT.

Source: Eclipsewise.com

View at EarthSky Community Photos. | Robert Hall in South Mississippi took this image of the lunar eclipse on November 19, 2021. He wrote: “The moon turned red once it was 90% eclipsed.” Thank you, Robert! See more lunar eclipse photos below.

Visit timeanddate.com to get an exact timing of the eclipse from your location.

Animated map of the lunar eclipse.

How long will it last?

From start to finish, the eclipse will last 339 minutes. And the moon will be in Earth’s dark shadow – for the partial eclipse – for 199 minutes.

Read more: Why no eclipse at every full and new moon?

During a lunar eclipse, Earth’s shadow falls on the moon. So if the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. But if the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via timeanddate.com. Used with permission.

Moon and Soros

The moment of greatest eclipse takes place 5.8 days after the moon reaches apogee, its farthest point from Earth for the month.

The Saros catalog describes the periodicity of eclipses. This August 27-28 total lunar eclipse belongs to Saros 138. It is number 29 of 82 lunar eclipses in the series. All eclipses in this series occur at the moon’s ascending node. The moon moves southward with respect to the node with each succeeding eclipse in the series.

The instant of greatest eclipse – when the axis of the moon’s shadow cone passes closest to Earth’s center – takes place at 4:12 UTC on August 28. The moon will lie at zenith – directly overhead – at a point in the Brazilian Amazon.

Who can see lunar eclipses?

A full moon is up only at night. And a total lunar eclipse is visible from all parts of Earth that are experiencing night while the eclipse is taking place. But some will see the eclipse more clearly, or more thoroughly, than others, depending on location. For example, some will see it at moonrise or moonset, when the moon is low in the sky.

View at EarthSky Community Photos. | Atharva Maurya captured this image on March 3, 2026, from India and wrote: “This image showcases the different phases of lunar eclipse of March 3, 2026.” Thank you, Atharva!

The constellation behind the partial lunar eclipse

The August 28, 2026, partial lunar eclipse occurs when the moon is in the constellation of Aquarius the Water Bearer.

Find the moon’s path with respect to Earth’s umbral and penumbral shadows below.

A map for the partial lunar eclipse on August 27-28, 2026. It sweeps across Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean. Areas in white on the map will see all of the partial eclipse. The line down the middle notes where the greatest eclipse occurs. Shaded areas will see part of the eclipse and dark areas are where the eclipse is not visible. Note the difference between UTC and TD (terrestrial dynamical time, often abbreviated TT as well). Key to lunar eclipse maps here. Image via Fred Espenak/ EclipseWise. Used with permission.

Maps and data for the total lunar eclipse

• Detailed lunar eclipse figure
• Visual Appearance of Lunar Eclipses
• Danjon Scale of Lunar Eclipse Brightness
• August 28, 2028, eclipse map animation

More resources

See Spectacular total lunar eclipse images from March 2-3, 2026

How to photograph a lunar eclipse

Submit your lunar eclipse photo to EarthSky here.

EarthSky’s monthly night sky guide: Visible planets and more

Bottom line: A deep partial lunar eclipse takes place on August 27-28, 2026, visible in Africa, Europe, Scandinavia, Iceland, parts of Greenland, Antarctica, most of the Americas and eastern Pacific Ocean. Maps and details here.

The post Deep partial lunar eclipse of the August 27-28 Sturgeon Moon first appeared on EarthSky.

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Were these polygonal cracks on Venus once on a seafloor?

View larger. | Here’s a region of cracks on Venus, 2nd world outward from our sun. They might have formed on an ancient seafloor, scientists say. Image via Earth and Planetary Science Letters (2026) (CC BY 4.0).

• Venus is extremely hot and dry on its surface. But scientists think it once had much more water, perhaps even oceans.
• Large networks of polygonal cracks cover Venus’ surface in low-lying areas. A new study says they might have formed in seafloor mud as the water evaporated.
• It’s still a hypothesis right now, but it would support other studies postulating ancient oceans on Venus.

You deserve a daily dose of good news. For the latest in science and the night sky, click here to subscribe to our free daily newsletter.

Polygonal cracks on Venus: How did they form?

Much of Venus’ surface is covered in long cracks. And scientists are still debating how they formed. One possible explanation has been volcanic rock that cooled and contracted to form the cracks. But there’s another – and more exciting – possibility. Some of the cracks might have formed in seafloor mud. That’s what a team of researchers from University of London and Imperial College in the U.K. say in a new paper titled The Lost Oceans of Venus.

These vast, polygonal cracks are found in low-lying regions of Venus. And they do look very similar to ones in seafloor mud on Earth. Thick layers of waterlogged clay get buried, compacted and squeezed dry over time. Did the same thing happen on Venus?

The intriguing peer-reviewed findings were published in Earth and Planetary Science Letters on July 29, 2026.

View larger. | Here are the 6 types of cracks identified by the researchers. These cracks are found in low-lying areas on Venus. Image via Earth and Planetary Science Letters (2026) (CC BY 4.0).

View larger. | This diagram depicts the process of how the Venus cracks might have formed. Oceans evaporated, leaving salts behind. Mud on the former seabed dried up, creating the polygonal cracks. Image via Ghail et al./ Earth and Planetary Science Letters.

View larger. | This radar image of Venus’ surface, showing this cloud-covered world without its cloud cover, is a composite of data from NASA’s Magellan and Pioneer Venus Orbiter spacecraft. So we see Venus’ formerly hidden surface is tortured, with many cracks, valleys and volcanoes. Image via NASA/ JPL-Caltech.

6 types of cracks

Venus orbits the sun one step inward from Earth. Its cloud-covered surface has created a runaway greenhouse effect on the planet, giving it surface temperatures averaging roughly 464°C (867°F). So it’s hot enough on the surface of Venus to melt lead! And as a result we tend to think about Venus as a blazing hot world on its surface, which is also known to have features resembling volcanoes. But oceans on Venus? Could have happened?

The cracks might be evidence that it’s possible.

There are various types of cracks found on the surface of this neighboring world. One of them is composed of polygon shapes, in low-lying plains. Each polygon is about 1 to 2 kilometers (0.6 to 1.2 miles) across. The researchers then further divided these polygons into six distinct types. And, they say, the patterns overall are much more similar to cracks in dried-out seabeds than to cracks formed by volcanoes.

Similar cracks on Earth can be found in the Mediterranean Sea. A long time ago, almost 6 million years, it almost completely dried up. As the water gradually evaporated, it left behind thick salt deposits and cracks, like what we see on Venus.

Plus, there are also long, winding channels on Venus called canali by scientists. For some years, scientists have thought that flowing lava formed them. But they’re also similar to channels carved on seafloors.

In addition, wrinkled ridges in the lowlands might be above salt deposits, similar to on Earth.

Another recent study found concentric rings in Venus’ atmosphere! On the left, an unpolarized view of the cloud tops of Venus shows a smooth, regular brightness. On the right, a view in polarized light reveals a set of concentric rings – really, atmospheric ripples – in the dense, high atmosphere. Image via Gourav Mahapatra/ The Planetary Science Journal.

The debate continues

These researchers have presented an interesting, even compelling, scenario. But it’s not proof yet of an ancient ocean on Venus. That will require more study to confirm, or not.

And some other studies have been doubtful about long-lost Venusian oceans.

So the debate will continue, until definitive evidence is found of ancient oceans on Venus. That might require future missions that will study the surface and atmosphere in unprecedented detail.

In another recent study, researchers discovered concentric rings in Venus’ atmosphere, above its thick layers of clouds. The rings are actually waves or ripples, but very ring-like!

Bottom line: Sprawling, huge cracks on Venus have long puzzled scientists. A new study suggests the polygon shapes formed from drying mud on an ancient seafloor.

Source: The lost oceans of Venus

Via Phys.org

Read more: Venus rings found high above the planet’s thick clouds

Read more: New study says water in Venus’ clouds surprisingly abundant

The post Were these polygonal cracks on Venus once on a seafloor? first appeared on EarthSky.

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View larger. | Here’s a region of cracks on Venus, 2nd world outward from our sun. They might have formed on an ancient seafloor, scientists say. Image via Earth and Planetary Science Letters (2026) (CC BY 4.0).

• Venus is extremely hot and dry on its surface. But scientists think it once had much more water, perhaps even oceans.
• Large networks of polygonal cracks cover Venus’ surface in low-lying areas. A new study says they might have formed in seafloor mud as the water evaporated.
• It’s still a hypothesis right now, but it would support other studies postulating ancient oceans on Venus.

You deserve a daily dose of good news. For the latest in science and the night sky, click here to subscribe to our free daily newsletter.

Polygonal cracks on Venus: How did they form?

Much of Venus’ surface is covered in long cracks. And scientists are still debating how they formed. One possible explanation has been volcanic rock that cooled and contracted to form the cracks. But there’s another – and more exciting – possibility. Some of the cracks might have formed in seafloor mud. That’s what a team of researchers from University of London and Imperial College in the U.K. say in a new paper titled The Lost Oceans of Venus.

These vast, polygonal cracks are found in low-lying regions of Venus. And they do look very similar to ones in seafloor mud on Earth. Thick layers of waterlogged clay get buried, compacted and squeezed dry over time. Did the same thing happen on Venus?

The intriguing peer-reviewed findings were published in Earth and Planetary Science Letters on July 29, 2026.

View larger. | Here are the 6 types of cracks identified by the researchers. These cracks are found in low-lying areas on Venus. Image via Earth and Planetary Science Letters (2026) (CC BY 4.0).

View larger. | This diagram depicts the process of how the Venus cracks might have formed. Oceans evaporated, leaving salts behind. Mud on the former seabed dried up, creating the polygonal cracks. Image via Ghail et al./ Earth and Planetary Science Letters.

View larger. | This radar image of Venus’ surface, showing this cloud-covered world without its cloud cover, is a composite of data from NASA’s Magellan and Pioneer Venus Orbiter spacecraft. So we see Venus’ formerly hidden surface is tortured, with many cracks, valleys and volcanoes. Image via NASA/ JPL-Caltech.

6 types of cracks

Venus orbits the sun one step inward from Earth. Its cloud-covered surface has created a runaway greenhouse effect on the planet, giving it surface temperatures averaging roughly 464°C (867°F). So it’s hot enough on the surface of Venus to melt lead! And as a result we tend to think about Venus as a blazing hot world on its surface, which is also known to have features resembling volcanoes. But oceans on Venus? Could have happened?

The cracks might be evidence that it’s possible.

There are various types of cracks found on the surface of this neighboring world. One of them is composed of polygon shapes, in low-lying plains. Each polygon is about 1 to 2 kilometers (0.6 to 1.2 miles) across. The researchers then further divided these polygons into six distinct types. And, they say, the patterns overall are much more similar to cracks in dried-out seabeds than to cracks formed by volcanoes.

Similar cracks on Earth can be found in the Mediterranean Sea. A long time ago, almost 6 million years, it almost completely dried up. As the water gradually evaporated, it left behind thick salt deposits and cracks, like what we see on Venus.

Plus, there are also long, winding channels on Venus called canali by scientists. For some years, scientists have thought that flowing lava formed them. But they’re also similar to channels carved on seafloors.

In addition, wrinkled ridges in the lowlands might be above salt deposits, similar to on Earth.

Another recent study found concentric rings in Venus’ atmosphere! On the left, an unpolarized view of the cloud tops of Venus shows a smooth, regular brightness. On the right, a view in polarized light reveals a set of concentric rings – really, atmospheric ripples – in the dense, high atmosphere. Image via Gourav Mahapatra/ The Planetary Science Journal.

The debate continues

These researchers have presented an interesting, even compelling, scenario. But it’s not proof yet of an ancient ocean on Venus. That will require more study to confirm, or not.

And some other studies have been doubtful about long-lost Venusian oceans.

So the debate will continue, until definitive evidence is found of ancient oceans on Venus. That might require future missions that will study the surface and atmosphere in unprecedented detail.

In another recent study, researchers discovered concentric rings in Venus’ atmosphere, above its thick layers of clouds. The rings are actually waves or ripples, but very ring-like!

Bottom line: Sprawling, huge cracks on Venus have long puzzled scientists. A new study suggests the polygon shapes formed from drying mud on an ancient seafloor.

Source: The lost oceans of Venus

Via Phys.org

Read more: Venus rings found high above the planet’s thick clouds

Read more: New study says water in Venus’ clouds surprisingly abundant

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