Cygnus the Swan flies along the Milky Way

Cygnus the Swan’s brightest star, Deneb, marks one of the corners of the Summer Triangle. And its bright double star, Albireo, is one of the finest in the heavens.

If you have a dark sky, you can observe the edgewise view into our own galaxy – our Milky Way – spanning across the heavens. As you gaze toward it, you’ll also be looking toward the constellation Cygnus the Swan. Its brightest star is called Deneb, the Swan’s Tail.

Additionally, the constellation Cygnus contains one of the most beloved double stars in the sky, Albireo, whose two component stars appear blue and gold.

The constellation Cygnus – with its noticeable stars Deneb and Albireo – are sometimes called the Northern Cross.

Plus, the star Deneb marks one of the corners of the famous Summer Triangle, an asterism composed of three bright stars in three different constellations.

So there’s a lot going on in this part of the sky! And no wonder, because the Swan lets you peer into the depths of the Milky Way.

How to find Cygnus from the Northern Hemisphere

You can find Cygnus high above the eastern horizon after sunset in the evening in June. As the sky grows dark, the first of its stars that you’ll see is Deneb, because it’s so bright. It’s the brightest in its constellation at magnitude 1.25.

Later, as June nights wear on, you’ll be able to trace out the body of the Swan and its bent wings. Then, you can find the double star, Albireo, which marks its head.

If you can find the large Summer Triangle shape, Deneb in Cygnus is the star that lies toward the northeast.

Then – assuming you have a dark sky – you can look along the length of Cygnus to see the hazy “cloud” behind it. It isn’t a true cloud, but a vast collection of billions our stars: our home galaxy, the Milky Way. You’ll notice the Milky Way runs along the same axis as the long line of the body of the Swan.

The bright star Deneb is part of the famous Summer Triangle asterism. Its constellation, Cygnus the Swan, flies across the northern summer evening sky.

The Swan in skylore

The mythology of Cygnus tells the story of Zeus, who changed into the form of a swan to entice Queen Leda. From their union came the twins Castor and Pollux.

It’s said that, today, we see Castor and Pollux as the bright stars of the constellation Gemini the Twins.

Stars of the Swan

Deneb, or Alpha Cygni, is the 19th brightest star in the sky. At magnitude 1.25, it’s a blue-white supergiant star lying about 1,500 light-years away, which is a long distance for a star that shines so brightly in our skies.

Albireo, the head of the Swan, is one of the most beautiful double stars in the heavens. And, with a small telescope, you can easily divide Albireo into a larger yellow star and smaller blue star. The brighter star of Albireo (or Beta Cygni) is magnitude 3.1, and the dimmer is magnitude 5.8. The stars are approximately 380 light-years distant.

Omicron Cygni, or 30 and 31 Cygni, is a double star with orange and blue components that you can see with binoculars. These stars lie between Deneb and Delta Cygni, which is the western wing of the Swan. At magnitudes 4.8 and 3.8, 30 and 31 Cygni lie 610 and 1.350 light-years away, respectively.

Gliese 777 is a yellow subgiant star shining at 5.71 magnitude and located about 51 light-years distant. Three extrasolar planets have been confirmed in its system.

The constellation Cygnus with its stars, that form an asterism known as the Northern Cross. Image via IAU/ Sky & Telescope/ Wikimedia Commons (CC BY 4.0).

Deep-sky objects in Cygnus

In addition, you can find an open cluster in Cygnus lying less than 2 degrees from Sadr, or Gamma Cygni, the 3rd brightest star of the constellation, at magnitude 2.23, at the center of the cross or Swan. This open cluster is M29, at magnitude 7.1. With this in mind, try using binoculars to track it down.

Also, another Messier object in Cygnus is M39, an open cluster lying about 9 degrees northeast of Deneb. M39 is magnitude 5.5. In this case, you can try to spot with just your eyes alone.

Sadr and star clusters

Now, head back to Sadr. A 7.4-magnitude open cluster, NGC 6910, lies just 1/2 degree north of the star. Then scanning along the western boundary of Cygnus with binoculars or a telescope reveals other clusters, including the magnitude 7.3 Foxhead Cluster (NGC 6819) and the 6.8-magnitude Hole-in-a-Cluster (NGC 6811).

Also, on the western side of the constellation, 5 1/2 degrees north of Sadr, or Gamma Cygni, is the 8.8 magnitude Blinking Planetary, NGC 6826. To be sure, as you move your eyes across it, does it appear to blink?

View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured this wide-field view of diffuse nebulae in Cygnus on September 24, 2024. Andy wrote: “As the moon continues to come up later, I have been experimenting with wide-angle photos. Cygnus is such a treat because there are so many spectacular objects quite close together and this pic shows them.” It sure does show a lot of objects. Thank you, Andy!

North America and Veil nebulae

The North America Nebula, or NGC 7000, lies a little over 3 degrees east of Deneb. When you look at it in photos, can you trace out the shape of the continent for which it’s named? You can glimpse this large nebula under dark skies with binoculars. In fact, it extends up to four moon-widths. Depending on your vision and sky conditions, you might detect this large 4.4 magnitude nebula with your eyes alone.

View at EarthSky Community Photos. | Rui Santos captured this image on July 9, 2025, from Portugal and wrote: “The Western Veil nebula, located in the constellation Cygnus, is part of a supernova remnant, so it’s the remains of a massive star that exploded around 8,000 years ago. It’s about 2,400 light-years from Earth, and had nearly 20 times the mass of our sun! The explosion was so powerful that it hurled the star’s outer layers into space at incredibly high speeds. That formed these filament-like structures that glow as they collide with interstellar gas. It’s amazing to think that such a catastrophic event could leave behind something so incredibly beautiful.” It’s also known as the Witch’s Broom. Thank you, Rui!

View at EarthSky Community Photos. | Robert R. Gaudet in Pennfield, New Brunswick, Canada, captured this telescopic view of the North America Nebula, in the constellation Cygnus, on June 26, 2025. Robert wrote: “Just a beautiful night in Pennfield, New Brunswick Canada, that I couldn’t pass up imaging the Cygnus Wall portion of NGC 7000 or the North America Nebula.” Thank you, Robert!

Cygnus is great to explore with binoculars

In addition to the objects mentioned above, you can explore Cygnus in binoculars. That’s because the Milky Way makes a rich background in this part of the sky. So you can find many more nebulae and clusters if you’re patient and sweep the area with binoculars. You might catch even more with a telescope.

Cygnus From The South

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

For observers in the Southern Hemisphere, Cygnus is a winter constellation that appears effectively upside down from our perspective. From far southern locations such as New Zealand’s South Island (around 45°S latitude), the constellation never fully rises above the horizon.

The star Albireo—the Swan’s head—becomes the highest point of the constellation, giving the impression of the swan flying up from beyond the northern horizon. Albireo reaches an altitude of approximately 17° above the horizon, while the constellation’s brightest star, Deneb, resides on or below the horizon from much of New Zealand’s South Island and cannot be seen.

Further north, Cygnus becomes progressively more visible as the swan flies higher into the sky. From Christchurch (43.5°S), Deneb just skims above the horizon at culmination, while from Wellington (41.3°S) it reaches around 4° altitude. In Auckland (36.8°S), Deneb climbs to approximately 9° above the northern horizon, and from Brisbane, Australia (27.5°S), it reaches about 18°.

Even from these locations, however, Deneb remains a low-altitude object, often affected by atmospheric haze and extinction.
Despite this, several of Cygnus’s most famous deep-sky objects become accessible from southern latitudes. The Veil Nebula with its rich filamentary structures climbs high enough above the horizon to become a viable target for astrophotographers.

Bottom line: Cygnus the Swan is a constellation that lies in front of the starlit band of the Milky Way. Its brightest star, Deneb, is part of the Summer Triangle.

Read more: Why 61 Cygni is nicknamed Flying Star

The post Cygnus the Swan flies along the Milky Way first appeared on EarthSky.

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Cygnus the Swan’s brightest star, Deneb, marks one of the corners of the Summer Triangle. And its bright double star, Albireo, is one of the finest in the heavens.

If you have a dark sky, you can observe the edgewise view into our own galaxy – our Milky Way – spanning across the heavens. As you gaze toward it, you’ll also be looking toward the constellation Cygnus the Swan. Its brightest star is called Deneb, the Swan’s Tail.

Additionally, the constellation Cygnus contains one of the most beloved double stars in the sky, Albireo, whose two component stars appear blue and gold.

The constellation Cygnus – with its noticeable stars Deneb and Albireo – are sometimes called the Northern Cross.

Plus, the star Deneb marks one of the corners of the famous Summer Triangle, an asterism composed of three bright stars in three different constellations.

So there’s a lot going on in this part of the sky! And no wonder, because the Swan lets you peer into the depths of the Milky Way.

How to find Cygnus from the Northern Hemisphere

You can find Cygnus high above the eastern horizon after sunset in the evening in June. As the sky grows dark, the first of its stars that you’ll see is Deneb, because it’s so bright. It’s the brightest in its constellation at magnitude 1.25.

Later, as June nights wear on, you’ll be able to trace out the body of the Swan and its bent wings. Then, you can find the double star, Albireo, which marks its head.

If you can find the large Summer Triangle shape, Deneb in Cygnus is the star that lies toward the northeast.

Then – assuming you have a dark sky – you can look along the length of Cygnus to see the hazy “cloud” behind it. It isn’t a true cloud, but a vast collection of billions our stars: our home galaxy, the Milky Way. You’ll notice the Milky Way runs along the same axis as the long line of the body of the Swan.

The bright star Deneb is part of the famous Summer Triangle asterism. Its constellation, Cygnus the Swan, flies across the northern summer evening sky.

The Swan in skylore

The mythology of Cygnus tells the story of Zeus, who changed into the form of a swan to entice Queen Leda. From their union came the twins Castor and Pollux.

It’s said that, today, we see Castor and Pollux as the bright stars of the constellation Gemini the Twins.

Stars of the Swan

Deneb, or Alpha Cygni, is the 19th brightest star in the sky. At magnitude 1.25, it’s a blue-white supergiant star lying about 1,500 light-years away, which is a long distance for a star that shines so brightly in our skies.

Albireo, the head of the Swan, is one of the most beautiful double stars in the heavens. And, with a small telescope, you can easily divide Albireo into a larger yellow star and smaller blue star. The brighter star of Albireo (or Beta Cygni) is magnitude 3.1, and the dimmer is magnitude 5.8. The stars are approximately 380 light-years distant.

Omicron Cygni, or 30 and 31 Cygni, is a double star with orange and blue components that you can see with binoculars. These stars lie between Deneb and Delta Cygni, which is the western wing of the Swan. At magnitudes 4.8 and 3.8, 30 and 31 Cygni lie 610 and 1.350 light-years away, respectively.

Gliese 777 is a yellow subgiant star shining at 5.71 magnitude and located about 51 light-years distant. Three extrasolar planets have been confirmed in its system.

The constellation Cygnus with its stars, that form an asterism known as the Northern Cross. Image via IAU/ Sky & Telescope/ Wikimedia Commons (CC BY 4.0).

Deep-sky objects in Cygnus

In addition, you can find an open cluster in Cygnus lying less than 2 degrees from Sadr, or Gamma Cygni, the 3rd brightest star of the constellation, at magnitude 2.23, at the center of the cross or Swan. This open cluster is M29, at magnitude 7.1. With this in mind, try using binoculars to track it down.

Also, another Messier object in Cygnus is M39, an open cluster lying about 9 degrees northeast of Deneb. M39 is magnitude 5.5. In this case, you can try to spot with just your eyes alone.

Sadr and star clusters

Now, head back to Sadr. A 7.4-magnitude open cluster, NGC 6910, lies just 1/2 degree north of the star. Then scanning along the western boundary of Cygnus with binoculars or a telescope reveals other clusters, including the magnitude 7.3 Foxhead Cluster (NGC 6819) and the 6.8-magnitude Hole-in-a-Cluster (NGC 6811).

Also, on the western side of the constellation, 5 1/2 degrees north of Sadr, or Gamma Cygni, is the 8.8 magnitude Blinking Planetary, NGC 6826. To be sure, as you move your eyes across it, does it appear to blink?

View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured this wide-field view of diffuse nebulae in Cygnus on September 24, 2024. Andy wrote: “As the moon continues to come up later, I have been experimenting with wide-angle photos. Cygnus is such a treat because there are so many spectacular objects quite close together and this pic shows them.” It sure does show a lot of objects. Thank you, Andy!

North America and Veil nebulae

The North America Nebula, or NGC 7000, lies a little over 3 degrees east of Deneb. When you look at it in photos, can you trace out the shape of the continent for which it’s named? You can glimpse this large nebula under dark skies with binoculars. In fact, it extends up to four moon-widths. Depending on your vision and sky conditions, you might detect this large 4.4 magnitude nebula with your eyes alone.

View at EarthSky Community Photos. | Rui Santos captured this image on July 9, 2025, from Portugal and wrote: “The Western Veil nebula, located in the constellation Cygnus, is part of a supernova remnant, so it’s the remains of a massive star that exploded around 8,000 years ago. It’s about 2,400 light-years from Earth, and had nearly 20 times the mass of our sun! The explosion was so powerful that it hurled the star’s outer layers into space at incredibly high speeds. That formed these filament-like structures that glow as they collide with interstellar gas. It’s amazing to think that such a catastrophic event could leave behind something so incredibly beautiful.” It’s also known as the Witch’s Broom. Thank you, Rui!

View at EarthSky Community Photos. | Robert R. Gaudet in Pennfield, New Brunswick, Canada, captured this telescopic view of the North America Nebula, in the constellation Cygnus, on June 26, 2025. Robert wrote: “Just a beautiful night in Pennfield, New Brunswick Canada, that I couldn’t pass up imaging the Cygnus Wall portion of NGC 7000 or the North America Nebula.” Thank you, Robert!

Cygnus is great to explore with binoculars

In addition to the objects mentioned above, you can explore Cygnus in binoculars. That’s because the Milky Way makes a rich background in this part of the sky. So you can find many more nebulae and clusters if you’re patient and sweep the area with binoculars. You might catch even more with a telescope.

Cygnus From The South

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

For observers in the Southern Hemisphere, Cygnus is a winter constellation that appears effectively upside down from our perspective. From far southern locations such as New Zealand’s South Island (around 45°S latitude), the constellation never fully rises above the horizon.

The star Albireo—the Swan’s head—becomes the highest point of the constellation, giving the impression of the swan flying up from beyond the northern horizon. Albireo reaches an altitude of approximately 17° above the horizon, while the constellation’s brightest star, Deneb, resides on or below the horizon from much of New Zealand’s South Island and cannot be seen.

Further north, Cygnus becomes progressively more visible as the swan flies higher into the sky. From Christchurch (43.5°S), Deneb just skims above the horizon at culmination, while from Wellington (41.3°S) it reaches around 4° altitude. In Auckland (36.8°S), Deneb climbs to approximately 9° above the northern horizon, and from Brisbane, Australia (27.5°S), it reaches about 18°.

Even from these locations, however, Deneb remains a low-altitude object, often affected by atmospheric haze and extinction.
Despite this, several of Cygnus’s most famous deep-sky objects become accessible from southern latitudes. The Veil Nebula with its rich filamentary structures climbs high enough above the horizon to become a viable target for astrophotographers.

Bottom line: Cygnus the Swan is a constellation that lies in front of the starlit band of the Milky Way. Its brightest star, Deneb, is part of the Summer Triangle.

Read more: Why 61 Cygni is nicknamed Flying Star

The post Cygnus the Swan flies along the Milky Way first appeared on EarthSky.

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Mercury is farthest from the sunset on June 15

For all of us on Earth now, the sun’s innermost planet, Mercury, is in the west after sunset, below blazing Venus and Jupiter. A line between Venus and Jupiter more or less points to Mercury. This is the view from the Northern Hemisphere. Notice how the planets make a line extending above and to the left of the sunset point. Mercury is farthest from the sunset – at greatest elongation on June 15. But look soon! Mercury – sometimes calle the most elusive planet – will slip away again before the end of this month. Chart via EarthSky.

Mercury after sunset in June 2026

Where to look: Look west, in the sunset direction – shortly after sunset – for Mercury. The sky’s two brightest planets – Venus and Jupiter – will point to it. Mercury emerged in the evening twilight sometime in late May. Watch for the moon near Mercury on the evening of June 16.
Greatest elongation: Mercury is farthest from the sun on our sky’s dome at 20 UTC (3 p.m. CST) on June 15, 2026. At that time, Mercury will be 25 degrees from the sun in our sky. See a comparison of elongations, below.
Brightness: Mercury emerged in the evening sky late in May. Since then, it’s been shining at around 0.1 magnitude. At greatest elongation it’ll be farther from the sunset glare, shining around 0 magnitude and therefore brighter than most stars! In the evenings after greatest elongation, the innermost planet will drop rapidly closer to the horizon the rest of the month. And Jupiter will draw close enough that you can see both of them in a pair of binoculars. Mercury will be moving between Earth and the sun, with its illuminated side becoming less and less visible. It’ll disappear in early July and will reach inferior conjunction – when it passes between Earth and the sun – at 1 UTC on July 13.
Through a telescope: Mercury will appear about 38% illuminated at greatest elongation. It’ll measure 8.19 arcseconds across.
Constellation: Mercury will lie in front of the constellation Gemini the Twins at this elongation. Doubtless, the stars in this constellation will be lost in the twilight.
Note: As the innermost planet, Mercury is tied to the sun in our sky. As a result, it never ventures very far above the horizon after sunset. So as soon as the sun disappears below your horizon, your clock starts ticking. Will you see the glowing point of light that is Mercury before it drops below the horizon, following the setting sun?

Here are the planets from Earth’s Southern Hemisphere, in the west shortly after sunset. Same line of planets, but the perspective is different. See how a line between them points from the sunset point up and to the right? Chart via EarthSky.

Watch for the planets and young moon on June 16 and 17

The very young moon will appear near Mercury, Venus and Jupiter on the evening of June 16. Chart via EarthSky.

You’ll find the young moon near Mercury, Jupiter and Venus on the evening of June 17, too. Look west, shortly after the sun goes down. Also look for the glow of earthshine on the unlit portion of the moon. That’s sunlight bounced off Earth onto the moon’s surface. Chart via EarthSky.

What is greatest elongation?

The 3D view: At greatest elongation, we’re seeing Mercury to one side of the sun. The sky view: Greatest elongation means the distance between Mercury and the sunset is at its greatest. This chart is not to scale! When thinking about these worlds in space, you have to realize they are miniscule dots in contrast to the vast space around them. Chart via EarthSky.

For precise sun and Mercury setting times at your location:

timeanddate.com (worldwide)
Stellarium (online planetarium)

Mercury events in 2026

Jan 21, 2026: Superior conjunction (passes behind sun from Earth)
Feb 19, 2026: Greatest elongation (evening)
Mar 7, 2026: Inferior conjunction (races between Earth and sun)
Apr 3, 2026: Greatest elongation (morning)
May 14, 2026: Superior conjunction (passes behind sun from Earth)
Jun 15, 2026: Greatest elongation (evening)
Jul 13, 2026: Inferior conjunction (races between Earth and sun)
Aug 2, 2026: Greatest elongation (morning)
Aug 27, 2026: Superior conjunction (passes behind sun from Earth)
Oct 12, 2026: Greatest elongation (evening)
Nov 4, 2026: Inferior conjunction (races between Earth and sun)
Nov 21, 2026: Greatest elongation (morning)

Heliocentric view of Mercury June 2026

Heliocentric view of solar system, June 2026. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission. Plus Guy Ottewell explains heliocentric charts here.

A comparison of elongations

In June 2026, Mercury stretches out 25 degrees from the sun in our sky. In fact, the farthest from the sun that Mercury can ever appear on the sky’s dome is about 28 degrees. And the least distance is around 18 degrees.

Mercury (and Venus) elongations are better or worse depending on the time of the year they occur. So in 2026, the Northern Hemisphere will had the best evening apparition in February. And the Southern Hemisphere will have its best evening elongation of Mercury in October.

In the autumn for either hemisphere, the ecliptic – or path of the sun, moon and planets – makes a narrow angle to the horizon in the evening. But it makes a steep slant, nearly perpendicular, in the morning. So, in autumn from either hemisphere, morning elongations of Mercury are best. That’s when Mercury appears higher above the horizon and farther from the glow of the sun. However, evening elongations in autumn are harder to see.

In the spring for either hemisphere, the situation reverses. The ecliptic and horizon meet at a sharper angle on spring evenings and a narrower angle on spring mornings. So, in springtime for either hemisphere, evening elongations of Mercury are best. Meanwhile, morning elongations in springtime are harder to see.

Mercury elongations compared. Here, gray areas represent evening apparitions (eastward elongation). Blue areas represent morning apparitions (westward elongation). The top figures are the maximum elongations, reached at the top dates shown beneath. Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40 degrees north (thick line) and 35 degrees south (thin line). Likewise, maxima are reached at the parenthesized dates below (40 degrees north in bold). Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

More Mercury evening elongation comparisons for 2026

Mercury’s greatest evening elongations in 2026 from the Northern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

Mercury’s greatest evening elongations in 2026 from the Southern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

Bottom line: The sun’s innermost planet, Mercury, will be 25 degrees from the sunset when it reaches its greatest elongation at 20 UTC on June 15. Also, this is a decent evening apparition of Mercury in 2026 for both the Northern and Southern Hemispheres.

Submit your photos to EarthSky here.

Read about greatest elongations, superior and inferior conjunctions: Definitions for stargazers

The post Mercury is farthest from the sunset on June 15 first appeared on EarthSky.

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For all of us on Earth now, the sun’s innermost planet, Mercury, is in the west after sunset, below blazing Venus and Jupiter. A line between Venus and Jupiter more or less points to Mercury. This is the view from the Northern Hemisphere. Notice how the planets make a line extending above and to the left of the sunset point. Mercury is farthest from the sunset – at greatest elongation on June 15. But look soon! Mercury – sometimes calle the most elusive planet – will slip away again before the end of this month. Chart via EarthSky.

Mercury after sunset in June 2026

Where to look: Look west, in the sunset direction – shortly after sunset – for Mercury. The sky’s two brightest planets – Venus and Jupiter – will point to it. Mercury emerged in the evening twilight sometime in late May. Watch for the moon near Mercury on the evening of June 16.
Greatest elongation: Mercury is farthest from the sun on our sky’s dome at 20 UTC (3 p.m. CST) on June 15, 2026. At that time, Mercury will be 25 degrees from the sun in our sky. See a comparison of elongations, below.
Brightness: Mercury emerged in the evening sky late in May. Since then, it’s been shining at around 0.1 magnitude. At greatest elongation it’ll be farther from the sunset glare, shining around 0 magnitude and therefore brighter than most stars! In the evenings after greatest elongation, the innermost planet will drop rapidly closer to the horizon the rest of the month. And Jupiter will draw close enough that you can see both of them in a pair of binoculars. Mercury will be moving between Earth and the sun, with its illuminated side becoming less and less visible. It’ll disappear in early July and will reach inferior conjunction – when it passes between Earth and the sun – at 1 UTC on July 13.
Through a telescope: Mercury will appear about 38% illuminated at greatest elongation. It’ll measure 8.19 arcseconds across.
Constellation: Mercury will lie in front of the constellation Gemini the Twins at this elongation. Doubtless, the stars in this constellation will be lost in the twilight.
Note: As the innermost planet, Mercury is tied to the sun in our sky. As a result, it never ventures very far above the horizon after sunset. So as soon as the sun disappears below your horizon, your clock starts ticking. Will you see the glowing point of light that is Mercury before it drops below the horizon, following the setting sun?

Here are the planets from Earth’s Southern Hemisphere, in the west shortly after sunset. Same line of planets, but the perspective is different. See how a line between them points from the sunset point up and to the right? Chart via EarthSky.

Watch for the planets and young moon on June 16 and 17

The very young moon will appear near Mercury, Venus and Jupiter on the evening of June 16. Chart via EarthSky.

You’ll find the young moon near Mercury, Jupiter and Venus on the evening of June 17, too. Look west, shortly after the sun goes down. Also look for the glow of earthshine on the unlit portion of the moon. That’s sunlight bounced off Earth onto the moon’s surface. Chart via EarthSky.

What is greatest elongation?

The 3D view: At greatest elongation, we’re seeing Mercury to one side of the sun. The sky view: Greatest elongation means the distance between Mercury and the sunset is at its greatest. This chart is not to scale! When thinking about these worlds in space, you have to realize they are miniscule dots in contrast to the vast space around them. Chart via EarthSky.

For precise sun and Mercury setting times at your location:

timeanddate.com (worldwide)
Stellarium (online planetarium)

Mercury events in 2026

Jan 21, 2026: Superior conjunction (passes behind sun from Earth)
Feb 19, 2026: Greatest elongation (evening)
Mar 7, 2026: Inferior conjunction (races between Earth and sun)
Apr 3, 2026: Greatest elongation (morning)
May 14, 2026: Superior conjunction (passes behind sun from Earth)
Jun 15, 2026: Greatest elongation (evening)
Jul 13, 2026: Inferior conjunction (races between Earth and sun)
Aug 2, 2026: Greatest elongation (morning)
Aug 27, 2026: Superior conjunction (passes behind sun from Earth)
Oct 12, 2026: Greatest elongation (evening)
Nov 4, 2026: Inferior conjunction (races between Earth and sun)
Nov 21, 2026: Greatest elongation (morning)

Heliocentric view of Mercury June 2026

Heliocentric view of solar system, June 2026. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission. Plus Guy Ottewell explains heliocentric charts here.

A comparison of elongations

In June 2026, Mercury stretches out 25 degrees from the sun in our sky. In fact, the farthest from the sun that Mercury can ever appear on the sky’s dome is about 28 degrees. And the least distance is around 18 degrees.

Mercury (and Venus) elongations are better or worse depending on the time of the year they occur. So in 2026, the Northern Hemisphere will had the best evening apparition in February. And the Southern Hemisphere will have its best evening elongation of Mercury in October.

In the autumn for either hemisphere, the ecliptic – or path of the sun, moon and planets – makes a narrow angle to the horizon in the evening. But it makes a steep slant, nearly perpendicular, in the morning. So, in autumn from either hemisphere, morning elongations of Mercury are best. That’s when Mercury appears higher above the horizon and farther from the glow of the sun. However, evening elongations in autumn are harder to see.

In the spring for either hemisphere, the situation reverses. The ecliptic and horizon meet at a sharper angle on spring evenings and a narrower angle on spring mornings. So, in springtime for either hemisphere, evening elongations of Mercury are best. Meanwhile, morning elongations in springtime are harder to see.

Mercury elongations compared. Here, gray areas represent evening apparitions (eastward elongation). Blue areas represent morning apparitions (westward elongation). The top figures are the maximum elongations, reached at the top dates shown beneath. Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40 degrees north (thick line) and 35 degrees south (thin line). Likewise, maxima are reached at the parenthesized dates below (40 degrees north in bold). Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

More Mercury evening elongation comparisons for 2026

Mercury’s greatest evening elongations in 2026 from the Northern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

Mercury’s greatest evening elongations in 2026 from the Southern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2026 Astronomical Calendar. Used with permission.

Bottom line: The sun’s innermost planet, Mercury, will be 25 degrees from the sunset when it reaches its greatest elongation at 20 UTC on June 15. Also, this is a decent evening apparition of Mercury in 2026 for both the Northern and Southern Hemispheres.

Submit your photos to EarthSky here.

Read about greatest elongations, superior and inferior conjunctions: Definitions for stargazers

The post Mercury is farthest from the sunset on June 15 first appeared on EarthSky.

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Dark matter: How new telescopes might help us find it

Dark matter makes up a large proportion of galaxies like the Milky Way, but scientists are still figuring out what it is. New telescopes like the Rubin Observatory could help astronomers find dark matter. Image Rubin Observatory/ NOIRLab/ SLAC/ NSF/ DOE/ AURA/ B. Quint.

• Dark matter makes up about 85% of the universe’s matter, but cannot be seen directly.
• Researchers have found possible dark matter hints, but the evidence is not yet conclusive.
• New telescopes could help confirm whether these signals come from dark matter.

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

This article was originally published in The Conversation. Edits by EarthSky.

By Marco Ajello, Clemson University, and Christopher Karwin, Clemson University.

What is dark matter?

NASA’s plans to return astronauts to the moon through the Artemis program and ultimately send humans to Mars highlight just how far space exploration has come. Yet while the moon and Mars remain compelling destinations filled with scientific mysteries, looking beyond our solar system raises even deeper questions about the universe itself.

Among the biggest of those mysteries is matter: the substance that makes up everything around us. Surprisingly, most of the matter in the universe is invisible, and astronomers still do not know what it is.

Physicists estimate that about 85% of all matter is made of something we cannot see, touch or directly detect. This elusive substance is known as dark matter. It doesn’t emit light like stars or galaxies. The only reason scientists know it exists is because of its gravity.

Galaxies rotate too fast to be held together by just the matter that can be seen. Light bends more strongly than expected as it travels through space. Galaxies within clusters fly past one another much faster than they should based on their visible mass alone.

Based on data from across the cosmos, scientists keep coming to the same conclusion: There is something out there that cannot be seen, but whose presence is unmistakable. It’s a question that has intrigued astronomers like us for more than 50 years.

So what is dark matter, and why does it matter?

Entirely new kinds of particles?

Everything in our everyday world is made of atoms, which are combinations of protons, neutrons and electrons. These particles form stars, planets, people and everything you see.

Dark matter, scientists believe, is fundamentally different. It is likely made of entirely new kinds of particles yet to be discovered. Understanding what those particles are would fill a major gap in the scientific understanding of physics. But the importance of dark matter goes far beyond particle physics.

Dark matter played a crucial role in shaping the universe. Shortly after the Big Bang that kicked off the birth of the universe, it acted as a kind of gravitational scaffolding, helping ordinary matter clump together to form the first galaxies and stars. Even today, it acts as the invisible glue that holds galaxies together.

In other words, without dark matter, the universe as you know it might not exist.

How to search for the invisible

Because dark matter does not emit light, scientists must search for it indirectly. One promising approach is to look for the signals it might produce when its particles collide and destroy each other through a process known as annihilation.

This idea may sound exotic, but it has a familiar analogy. In medical imaging, devices such as positron emission tomography scanners, or PET scanners for short, detect radiation produced when particles of antimatter – positrons – annihilate with electrons, which are normal matter.

Antimatter is just a form of matter made of particles that have the same mass as ordinary matter, but opposite charges and quantum properties. The annihilation signals in PET scanners allow doctors to map cancerous tissues inside the human body.

Scientists hope something similar could happen with dark matter. If dark matter particles annihilate with each other, they may produce high-energy radiation called gamma rays. These gamma rays could act as fingerprints, revealing where dark matter is concentrated and its properties.

As astrophysicists who study gamma rays, we and our collaborators use space-based telescopes to search for these signals.

Visualization from the Aquarius Project, a high-resolution cosmological dark matter simulation. The image shows the dark matter structure on both large cosmological scales, left panel, and on the scale of the Milky Way. Image by Volker Springel/ Virgo Consortium/ The Aquarius Project.

A mysterious signal at the heart of our galaxy

One of the most powerful tools for this search is NASA’s Fermi Large Area Telescope, known as Fermi-LAT, which has been observing the gamma-ray sky since 2008. Gamma rays are the most energetic form of light, and they are produced by some of the universe’s most extreme phenomena.

For years, Fermi has detected an unexplained glow of gamma rays coming from the center of the Milky Way. Based on gravitational observations such as galaxy rotation curves, stellar motions and the bending of light, combined with cosmological simulations, astrophysicists expect this region to be extremely rich in dark matter, making it an intriguing place to look for annihilation signals.

Could this glow be evidence of dark matter?

Possibly. But there’s a complication: The center of our galaxy is also crowded with more conventional astrophysical gamma ray sources, such as rapidly spinning neutron stars, which are produced from the collapse of massive stars. These objects can produce gamma rays that mimic the expected signal from dark matter.

At the moment, scientists cannot say for certain what is causing the emission. The signal could be a breakthrough, or it could be something more ordinary.

Clues from smaller galaxies

To help resolve this mystery, researchers also study much smaller systems, known as dwarf galaxies, which orbit the Milky Way. These galaxies contain dark matter but relatively few other sources of gamma rays, making them cleaner environments to search for dark matter-related signals.

So far, no definitive detection has been made.

However, an analysis published in March 2024 led by our team at Clemson University found hints of a signal emerging from these dwarf galaxies, and updated results collected since have supported these findings.

Using the latest Fermi-LAT data, combined with an updated census of dwarf galaxies and improved estimates of their dark matter content, we searched for faint gamma-ray signals across the population of dwarf galaxies. This led us to uncover an excess of gamma rays that earlier studies had also hinted at. The more data we’ve collected, the more significant the excess appears to become.

The evidence is not yet strong enough to claim a detection of dark matter, but it is intriguing. The properties of this signal are also consistent with what scientists see in the center of the Milky Way. If both signals share the same origin, the case for dark matter would grow stronger.

The Fermi spacecraft surveys the sky searching indirectly for dark matter. Image via NASA/ Goddard Space Flight Center/ Chris Smith (USRA/ GESTAR).

The next decade could be decisive

Confirming a dark matter signal will require more data and better instruments working together.

Future observations from Fermi-LAT will continue to improve the sensitivity of these searches. Additionally, new facilities such as the Vera C. Rubin Observatory in Chile, are expected to discover more dwarf galaxies for researchers to study.

Another key mission is NASA’s Compton Spectrometer and Imager, or COSI, scheduled for launch in 2027. COSI will offer a new view of the gamma-ray sky and could help clear up several longstanding mysteries. Among these mysteries is yet another unexplained bright glow from the center of the galaxy, produced when electrons and positrons annihilate, just as in PET scans.

Despite discovering the annihilation signal more than 50 years ago, scientists still don’t know where these positrons are coming from. By mapping this emission in unprecedented detail, COSI could help reveal what’s producing the glow, and whether it might be connected to dark matter and other unexplained signals in the Milky Way.

Artist’s concept of the COSI telescope, which will study antimatter in the galaxy. Image by Northrop Grumman Systems Corporation.

Is it dark matter or something else?

These efforts, along with many other ongoing searches, may help determine whether scientists are truly seeing the fingerprints of dark matter or something else entirely.

As humans push further into space, from the moon to Mars and beyond, new worlds wait to be discovered. In parallel with the new age of space exploration, with each new observation, scientists may be getting closer to answering one of the most fundamental questions in physics.

By Marco Ajello, Professor of Physics and Astronomy, Clemson University and Christopher Karwin, Assistant Professor of Physics and Astronomy, Clemson University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: New telescopes might bring scientists closer to detecting dark matter. They could soon reveal signals that finally let us understand this mysterious substance.

Read more: Rubin Observatory launches real-time alert system

The post Dark matter: How new telescopes might help us find it first appeared on EarthSky.

from EarthSky https://ift.tt/LztWYZ9

Dark matter makes up a large proportion of galaxies like the Milky Way, but scientists are still figuring out what it is. New telescopes like the Rubin Observatory could help astronomers find dark matter. Image Rubin Observatory/ NOIRLab/ SLAC/ NSF/ DOE/ AURA/ B. Quint.

• Dark matter makes up about 85% of the universe’s matter, but cannot be seen directly.
• Researchers have found possible dark matter hints, but the evidence is not yet conclusive.
• New telescopes could help confirm whether these signals come from dark matter.

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

This article was originally published in The Conversation. Edits by EarthSky.

By Marco Ajello, Clemson University, and Christopher Karwin, Clemson University.

What is dark matter?

NASA’s plans to return astronauts to the moon through the Artemis program and ultimately send humans to Mars highlight just how far space exploration has come. Yet while the moon and Mars remain compelling destinations filled with scientific mysteries, looking beyond our solar system raises even deeper questions about the universe itself.

Among the biggest of those mysteries is matter: the substance that makes up everything around us. Surprisingly, most of the matter in the universe is invisible, and astronomers still do not know what it is.

Physicists estimate that about 85% of all matter is made of something we cannot see, touch or directly detect. This elusive substance is known as dark matter. It doesn’t emit light like stars or galaxies. The only reason scientists know it exists is because of its gravity.

Galaxies rotate too fast to be held together by just the matter that can be seen. Light bends more strongly than expected as it travels through space. Galaxies within clusters fly past one another much faster than they should based on their visible mass alone.

Based on data from across the cosmos, scientists keep coming to the same conclusion: There is something out there that cannot be seen, but whose presence is unmistakable. It’s a question that has intrigued astronomers like us for more than 50 years.

So what is dark matter, and why does it matter?

Entirely new kinds of particles?

Everything in our everyday world is made of atoms, which are combinations of protons, neutrons and electrons. These particles form stars, planets, people and everything you see.

Dark matter, scientists believe, is fundamentally different. It is likely made of entirely new kinds of particles yet to be discovered. Understanding what those particles are would fill a major gap in the scientific understanding of physics. But the importance of dark matter goes far beyond particle physics.

Dark matter played a crucial role in shaping the universe. Shortly after the Big Bang that kicked off the birth of the universe, it acted as a kind of gravitational scaffolding, helping ordinary matter clump together to form the first galaxies and stars. Even today, it acts as the invisible glue that holds galaxies together.

In other words, without dark matter, the universe as you know it might not exist.

How to search for the invisible

Because dark matter does not emit light, scientists must search for it indirectly. One promising approach is to look for the signals it might produce when its particles collide and destroy each other through a process known as annihilation.

This idea may sound exotic, but it has a familiar analogy. In medical imaging, devices such as positron emission tomography scanners, or PET scanners for short, detect radiation produced when particles of antimatter – positrons – annihilate with electrons, which are normal matter.

Antimatter is just a form of matter made of particles that have the same mass as ordinary matter, but opposite charges and quantum properties. The annihilation signals in PET scanners allow doctors to map cancerous tissues inside the human body.

Scientists hope something similar could happen with dark matter. If dark matter particles annihilate with each other, they may produce high-energy radiation called gamma rays. These gamma rays could act as fingerprints, revealing where dark matter is concentrated and its properties.

As astrophysicists who study gamma rays, we and our collaborators use space-based telescopes to search for these signals.

Visualization from the Aquarius Project, a high-resolution cosmological dark matter simulation. The image shows the dark matter structure on both large cosmological scales, left panel, and on the scale of the Milky Way. Image by Volker Springel/ Virgo Consortium/ The Aquarius Project.

A mysterious signal at the heart of our galaxy

One of the most powerful tools for this search is NASA’s Fermi Large Area Telescope, known as Fermi-LAT, which has been observing the gamma-ray sky since 2008. Gamma rays are the most energetic form of light, and they are produced by some of the universe’s most extreme phenomena.

For years, Fermi has detected an unexplained glow of gamma rays coming from the center of the Milky Way. Based on gravitational observations such as galaxy rotation curves, stellar motions and the bending of light, combined with cosmological simulations, astrophysicists expect this region to be extremely rich in dark matter, making it an intriguing place to look for annihilation signals.

Could this glow be evidence of dark matter?

Possibly. But there’s a complication: The center of our galaxy is also crowded with more conventional astrophysical gamma ray sources, such as rapidly spinning neutron stars, which are produced from the collapse of massive stars. These objects can produce gamma rays that mimic the expected signal from dark matter.

At the moment, scientists cannot say for certain what is causing the emission. The signal could be a breakthrough, or it could be something more ordinary.

Clues from smaller galaxies

To help resolve this mystery, researchers also study much smaller systems, known as dwarf galaxies, which orbit the Milky Way. These galaxies contain dark matter but relatively few other sources of gamma rays, making them cleaner environments to search for dark matter-related signals.

So far, no definitive detection has been made.

However, an analysis published in March 2024 led by our team at Clemson University found hints of a signal emerging from these dwarf galaxies, and updated results collected since have supported these findings.

Using the latest Fermi-LAT data, combined with an updated census of dwarf galaxies and improved estimates of their dark matter content, we searched for faint gamma-ray signals across the population of dwarf galaxies. This led us to uncover an excess of gamma rays that earlier studies had also hinted at. The more data we’ve collected, the more significant the excess appears to become.

The evidence is not yet strong enough to claim a detection of dark matter, but it is intriguing. The properties of this signal are also consistent with what scientists see in the center of the Milky Way. If both signals share the same origin, the case for dark matter would grow stronger.

The Fermi spacecraft surveys the sky searching indirectly for dark matter. Image via NASA/ Goddard Space Flight Center/ Chris Smith (USRA/ GESTAR).

The next decade could be decisive

Confirming a dark matter signal will require more data and better instruments working together.

Future observations from Fermi-LAT will continue to improve the sensitivity of these searches. Additionally, new facilities such as the Vera C. Rubin Observatory in Chile, are expected to discover more dwarf galaxies for researchers to study.

Another key mission is NASA’s Compton Spectrometer and Imager, or COSI, scheduled for launch in 2027. COSI will offer a new view of the gamma-ray sky and could help clear up several longstanding mysteries. Among these mysteries is yet another unexplained bright glow from the center of the galaxy, produced when electrons and positrons annihilate, just as in PET scans.

Despite discovering the annihilation signal more than 50 years ago, scientists still don’t know where these positrons are coming from. By mapping this emission in unprecedented detail, COSI could help reveal what’s producing the glow, and whether it might be connected to dark matter and other unexplained signals in the Milky Way.

Artist’s concept of the COSI telescope, which will study antimatter in the galaxy. Image by Northrop Grumman Systems Corporation.

Is it dark matter or something else?

These efforts, along with many other ongoing searches, may help determine whether scientists are truly seeing the fingerprints of dark matter or something else entirely.

As humans push further into space, from the moon to Mars and beyond, new worlds wait to be discovered. In parallel with the new age of space exploration, with each new observation, scientists may be getting closer to answering one of the most fundamental questions in physics.

By Marco Ajello, Professor of Physics and Astronomy, Clemson University and Christopher Karwin, Assistant Professor of Physics and Astronomy, Clemson University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: New telescopes might bring scientists closer to detecting dark matter. They could soon reveal signals that finally let us understand this mysterious substance.

Read more: Rubin Observatory launches real-time alert system

The post Dark matter: How new telescopes might help us find it first appeared on EarthSky.

from EarthSky https://ift.tt/LztWYZ9

Earliest sunrises come before the summer solstice

The year’s earliest sunrises don’t happen on the summer solstice. For much of the Northern Hemisphere, they’re happening now. In the Southern Hemisphere, it’s the earliest sunsets that come before the winter solstice in June. The yearly cycle of sunrise and sunset times is easy to miss. But once you start noticing this cycle, it reveals the deeper rhythm of Earth’s journey around the sun … and your place in it.

When to look: The exact dates of the earliest sunrises vary with latitude. For example, for the Northern Hemisphere, the earliest sunrises can come as early as late May. For the southern U.S., the earliest sunrises begin in early June and stretch for weeks. At more northerly latitude, they happen closer to the summer solstice.
Southern Hemisphere? Your earliest sunsets happen before your summer solstice, too, in December. And right now, before your winter solstice, you’re having your earliest sunsets.
When is June solstice? The June solstice – summer solstice for the Northern Hemisphere, winter solstice for the Southern Hemisphere – will fall at 8:25 UTC (3:25 a.m. CDT) on June 21. Read: All you need to know about the June solstice.
For the Northern Hemisphere: Have you noticed how early your sunrises are? The dawn light is beautiful. Check a sunrise/sunset calendar for June. It’s likely your earliest sunrises are happening now, have just happened, or will happen in the coming week or so.
For the Southern Hemisphere: If you relish the daylight, as many do, you’ll be glad to know your sunsets will soon be shifting later! They’ll start shifting before your winter solstice – and shortest day – at the June solstice.

The sun rising over the Atlantic Ocean from St. Simons Island, Georgia. Image via Marcy Curran.

Earliest sunrises vary with latitude

The exact dates of your earliest sunrises (and earliest sunsets) vary with latitude.

• At the latitude of Mexico City (about 20 degrees N. latitude) the earliest sunrises are in early June.
• At the latitude of New Orleans, Cairo in Egypt and Chengdu in China (about 30 degrees N.), the earliest sunrises shift later, to around June 10.
• At the latitude of Philadelphia, Madrid in Spain or northern Japan (about 40 degrees N.) the earliest sunrises of the year happen on and near June 14.
• And the farther north you go, the closer your earliest sunrises come to the June solstice. By the time you get up to Seattle or Vancouver, they happen only a few days before the solstice.

If you keep going north, you eventually reach a geographic boundary where the concept of “earliest sunrise before the summer solstice” completely breaks down. That is, you reach the Arctic Circle (66.5 degrees N), above which the sun doesn’t rise or set in the weeks or months around the solstice. The concepts of daily “sunrise” and “sunset” disappear entirely, and you get one prolonged period of continuous daylight.

Rupesh Sangoi in Mumbai, India, captured separate images of the sunrise, showing the sun’s movement along the horizon, between the June and December solstices and on the equinoxes. Rupesh wrote: “Did this for over a year, at sunrise.” Glorious composite, Rupesh! Thank you.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Why aren’t the earliest sunrises on the solstice?

To understand why the earliest sunrises aren’t on the day of the solstice, you have to think about clocks and the spinning Earth.

Earth’s spin gives us the length of the day. One spin of the Earth = one day. And we humans have made clocks to measure that day length.

But clocks click along regularly … and Earth’s spin isn’t as regular. If you were to measure the time it takes for the Earth to rotate once relative to the sun – spanning from one local solar noon (when the sun reaches its highest point in your sky) to the next – you’d find the time from one solar noon to another is rarely exactly 24 hours.

Why isn’t it? Two main reasons: the tilt of Earth’s axis and the shape of Earth’s orbit. It’s the continual overlapping of these two cycles that gives us the earliest sunrises before the summer solstice.

Look at it this way. In June, the day (as measured by successive returns of the midday sun) is nearly 1/4 minute longer than 24 hours. So the midday sun (solar noon) comes later by the clock on the June solstice than it does one week before. And that means the sunrise and sunset times also come later by the clock.

Want a deeper explanation? Look up the Equation of Time.

The table below might help you get a sense of it.

Chart data via Timeanddate.com.

Why before the summer solstice, not after?

The primary reason for the earliest sunrise preceding the summer solstice is the inclination of the Earth’s rotational axis. For example, the earliest sunrise would take place before the solstice even if the Earth went around the sun in a circular orbit.

But the Earth’s elliptical orbit does make the phenomenon more extreme. At the June solstice, Earth in its orbit is rather close to our early July aphelion, our farthest point from the sun. We’re moving slowest in orbit. And this lessens the effect.

On the other hand, at the December solstice, Earth is rather close to our early January perihelion, our closest point to the sun. At that time, we’re moving fastest in orbit, and that accentuates the effect.

So there are little effects related to Earth’s orbit. But the sequence is always the same. Earliest sunrise, summer solstice, latest sunset in summer. Earliest sunset, winter solstice, latest sunrise in winter.

That’s true for you whether you’re in Earth’s Northern or Southern Hemisphere.

And it’s true whether your winter or summer happens when Earth is closest to the sun, or farthest from the sun.

View at EarthSky Community Photos. | Our friend Cecille Kennedy in Oregon took this photo of the setting sun on June 1, 2026. Thank you, Cecille! The Northern Hemisphere has the earliest sunrises before the June solstice.

View at EarthSky Community Photos. | Prateek Pandey captured this sunset view in Pachmari, Madhya Pradesh, India, on January 3, 2025. Beautiful!

Bottom line: Are you an early riser? If so – and you live in the Northern Hemisphere – you might know your earliest sunrises of the year are happening now. Southern Hemisphere? Your earliest sunsets are around now.

The post Earliest sunrises come before the summer solstice first appeared on EarthSky.

from EarthSky https://ift.tt/KiReaP4

The year’s earliest sunrises don’t happen on the summer solstice. For much of the Northern Hemisphere, they’re happening now. In the Southern Hemisphere, it’s the earliest sunsets that come before the winter solstice in June. The yearly cycle of sunrise and sunset times is easy to miss. But once you start noticing this cycle, it reveals the deeper rhythm of Earth’s journey around the sun … and your place in it.

When to look: The exact dates of the earliest sunrises vary with latitude. For example, for the Northern Hemisphere, the earliest sunrises can come as early as late May. For the southern U.S., the earliest sunrises begin in early June and stretch for weeks. At more northerly latitude, they happen closer to the summer solstice.
Southern Hemisphere? Your earliest sunsets happen before your summer solstice, too, in December. And right now, before your winter solstice, you’re having your earliest sunsets.
When is June solstice? The June solstice – summer solstice for the Northern Hemisphere, winter solstice for the Southern Hemisphere – will fall at 8:25 UTC (3:25 a.m. CDT) on June 21. Read: All you need to know about the June solstice.
For the Northern Hemisphere: Have you noticed how early your sunrises are? The dawn light is beautiful. Check a sunrise/sunset calendar for June. It’s likely your earliest sunrises are happening now, have just happened, or will happen in the coming week or so.
For the Southern Hemisphere: If you relish the daylight, as many do, you’ll be glad to know your sunsets will soon be shifting later! They’ll start shifting before your winter solstice – and shortest day – at the June solstice.

The sun rising over the Atlantic Ocean from St. Simons Island, Georgia. Image via Marcy Curran.

Earliest sunrises vary with latitude

The exact dates of your earliest sunrises (and earliest sunsets) vary with latitude.

• At the latitude of Mexico City (about 20 degrees N. latitude) the earliest sunrises are in early June.
• At the latitude of New Orleans, Cairo in Egypt and Chengdu in China (about 30 degrees N.), the earliest sunrises shift later, to around June 10.
• At the latitude of Philadelphia, Madrid in Spain or northern Japan (about 40 degrees N.) the earliest sunrises of the year happen on and near June 14.
• And the farther north you go, the closer your earliest sunrises come to the June solstice. By the time you get up to Seattle or Vancouver, they happen only a few days before the solstice.

If you keep going north, you eventually reach a geographic boundary where the concept of “earliest sunrise before the summer solstice” completely breaks down. That is, you reach the Arctic Circle (66.5 degrees N), above which the sun doesn’t rise or set in the weeks or months around the solstice. The concepts of daily “sunrise” and “sunset” disappear entirely, and you get one prolonged period of continuous daylight.

Rupesh Sangoi in Mumbai, India, captured separate images of the sunrise, showing the sun’s movement along the horizon, between the June and December solstices and on the equinoxes. Rupesh wrote: “Did this for over a year, at sunrise.” Glorious composite, Rupesh! Thank you.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Why aren’t the earliest sunrises on the solstice?

To understand why the earliest sunrises aren’t on the day of the solstice, you have to think about clocks and the spinning Earth.

Earth’s spin gives us the length of the day. One spin of the Earth = one day. And we humans have made clocks to measure that day length.

But clocks click along regularly … and Earth’s spin isn’t as regular. If you were to measure the time it takes for the Earth to rotate once relative to the sun – spanning from one local solar noon (when the sun reaches its highest point in your sky) to the next – you’d find the time from one solar noon to another is rarely exactly 24 hours.

Why isn’t it? Two main reasons: the tilt of Earth’s axis and the shape of Earth’s orbit. It’s the continual overlapping of these two cycles that gives us the earliest sunrises before the summer solstice.

Look at it this way. In June, the day (as measured by successive returns of the midday sun) is nearly 1/4 minute longer than 24 hours. So the midday sun (solar noon) comes later by the clock on the June solstice than it does one week before. And that means the sunrise and sunset times also come later by the clock.

Want a deeper explanation? Look up the Equation of Time.

The table below might help you get a sense of it.

Chart data via Timeanddate.com.

Why before the summer solstice, not after?

The primary reason for the earliest sunrise preceding the summer solstice is the inclination of the Earth’s rotational axis. For example, the earliest sunrise would take place before the solstice even if the Earth went around the sun in a circular orbit.

But the Earth’s elliptical orbit does make the phenomenon more extreme. At the June solstice, Earth in its orbit is rather close to our early July aphelion, our farthest point from the sun. We’re moving slowest in orbit. And this lessens the effect.

On the other hand, at the December solstice, Earth is rather close to our early January perihelion, our closest point to the sun. At that time, we’re moving fastest in orbit, and that accentuates the effect.

So there are little effects related to Earth’s orbit. But the sequence is always the same. Earliest sunrise, summer solstice, latest sunset in summer. Earliest sunset, winter solstice, latest sunrise in winter.

That’s true for you whether you’re in Earth’s Northern or Southern Hemisphere.

And it’s true whether your winter or summer happens when Earth is closest to the sun, or farthest from the sun.

View at EarthSky Community Photos. | Our friend Cecille Kennedy in Oregon took this photo of the setting sun on June 1, 2026. Thank you, Cecille! The Northern Hemisphere has the earliest sunrises before the June solstice.

View at EarthSky Community Photos. | Prateek Pandey captured this sunset view in Pachmari, Madhya Pradesh, India, on January 3, 2025. Beautiful!

Bottom line: Are you an early riser? If so – and you live in the Northern Hemisphere – you might know your earliest sunrises of the year are happening now. Southern Hemisphere? Your earliest sunsets are around now.

The post Earliest sunrises come before the summer solstice first appeared on EarthSky.

from EarthSky https://ift.tt/KiReaP4

What is airglow? This glowing light is not an aurora

View at EarthSky Community Photos. | Makrem Larnaout in Morneg, Tunisia, captured this image – with airglow – on June 18, 2023. Thank you, Makrem! And what a fantastic display! Read more about this image.

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.

What is airglow?

Airglow is the light of excited atoms high in Earth’s atmosphere. And it’s usually too faint for the eye alone to see. But under very dark skies, photographers can capture it. Here’s how NASA’s Earth Observatory describes airglow:

The phenomenon typically occurs when molecules (mostly nitrogen and oxygen) are energized by ultraviolet (UV) radiation from sunlight. To release that energy, atoms in the lower atmosphere bump into each other and lose energy in the collision. But the upper atmosphere is thinner, so atoms are less likely to collide. Instead, they release their energy by emitting photons. And the result is colorful airglow.

Collisions can create airglow, too

But some collisions can also create airglow. In fact, airglow is more common during solar maximum. That’s because the solar activity heats the upper atmosphere, which causes more collisions. Specifically, it causes more collisions that result in greenish light. Spaceweather.com said:

Although airglow does not require solar activity, there is a strong link to the solar cycle. As long ago as 1935, Lord Rayleigh realized that airglow peaks during years around solar maximum. Modern studies (e.g., 2011 and 2015 have confirmed the effect. And airglow is up to 40% brighter when the sun is most active.

Watch a video on airglow

And here’s another view of airglow from the International Space Station.

View larger. | Here, lightning, airglow and the Milky Way galaxy lit up the night sky as astronauts passed over Kiribati in the central Pacific. Read more about this image. Image via NASA Earth Observatory.

A photo gallery from our readers

If you have a recent photo of airglow to share, send it to us!

View at EarthSky Community Photos. | Julie Machado captured this image from New Zealand on November 16, 2025. Julie wrote: “This photo shows the faint red emission of the Gum Nebula above the mountains in Coromandel, New Zealand. The nebula is extremely large and very dim, but long-exposure imaging can reveal parts of its structure. The green band near the horizon is natural airglow.
And the sky and foreground were photographed on the same night from the same spot, with the sky taken on a tracked exposure and the landscape untracked. The image reflects the scene as it appeared that night.” Thank you, Julie!

View at EarthSky Community Photos. | Meiying Lee in Mount Cook National Park, New Zealand, captured the Milky Way on March 19, 2026. Meiying wrote: “The southern Milky Way rises directly from the horizon, shining with remarkable clarity. On the right side of the sky, 2 faint, cloud-like patches stand out. These are the Large and Small Magellanic Clouds, iconic features of the Southern Hemisphere. And near the horizon, subtle hues of green and red glow softly. This is airglow, quietly revealing just how pure and transparent the sky is here.” Thank you, Meiying!

View at EarthSky Community Photos. | Paolo Bardelli of Switzerland captured the sun’s counterglow – or gegenschein – on November 2, 2024, and wrote: “The elusive gegenschein phenomenon captured on a clear night from the Simplon Pass in Switzerland. The antisolar point is located in the top right image, barely visible as a very faint and diffuse nebulosity extending over 20 degrees in a sky with green and orange airglow. The image was highly contrasted to accentuate the phenomenon.” Thank you, Paolo.

Bottom line: Airglow is a light that occurs high in Earth’s atmosphere. It’s usually too dim to see with the eye, but photographers can capture glorious photographs of it.

The post What is airglow? This glowing light is not an aurora first appeared on EarthSky.

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View at EarthSky Community Photos. | Makrem Larnaout in Morneg, Tunisia, captured this image – with airglow – on June 18, 2023. Thank you, Makrem! And what a fantastic display! Read more about this image.

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What is airglow?

Airglow is the light of excited atoms high in Earth’s atmosphere. And it’s usually too faint for the eye alone to see. But under very dark skies, photographers can capture it. Here’s how NASA’s Earth Observatory describes airglow:

The phenomenon typically occurs when molecules (mostly nitrogen and oxygen) are energized by ultraviolet (UV) radiation from sunlight. To release that energy, atoms in the lower atmosphere bump into each other and lose energy in the collision. But the upper atmosphere is thinner, so atoms are less likely to collide. Instead, they release their energy by emitting photons. And the result is colorful airglow.

Collisions can create airglow, too

But some collisions can also create airglow. In fact, airglow is more common during solar maximum. That’s because the solar activity heats the upper atmosphere, which causes more collisions. Specifically, it causes more collisions that result in greenish light. Spaceweather.com said:

Although airglow does not require solar activity, there is a strong link to the solar cycle. As long ago as 1935, Lord Rayleigh realized that airglow peaks during years around solar maximum. Modern studies (e.g., 2011 and 2015 have confirmed the effect. And airglow is up to 40% brighter when the sun is most active.

Watch a video on airglow

And here’s another view of airglow from the International Space Station.

View larger. | Here, lightning, airglow and the Milky Way galaxy lit up the night sky as astronauts passed over Kiribati in the central Pacific. Read more about this image. Image via NASA Earth Observatory.

A photo gallery from our readers

If you have a recent photo of airglow to share, send it to us!

View at EarthSky Community Photos. | Julie Machado captured this image from New Zealand on November 16, 2025. Julie wrote: “This photo shows the faint red emission of the Gum Nebula above the mountains in Coromandel, New Zealand. The nebula is extremely large and very dim, but long-exposure imaging can reveal parts of its structure. The green band near the horizon is natural airglow.
And the sky and foreground were photographed on the same night from the same spot, with the sky taken on a tracked exposure and the landscape untracked. The image reflects the scene as it appeared that night.” Thank you, Julie!

View at EarthSky Community Photos. | Meiying Lee in Mount Cook National Park, New Zealand, captured the Milky Way on March 19, 2026. Meiying wrote: “The southern Milky Way rises directly from the horizon, shining with remarkable clarity. On the right side of the sky, 2 faint, cloud-like patches stand out. These are the Large and Small Magellanic Clouds, iconic features of the Southern Hemisphere. And near the horizon, subtle hues of green and red glow softly. This is airglow, quietly revealing just how pure and transparent the sky is here.” Thank you, Meiying!

View at EarthSky Community Photos. | Paolo Bardelli of Switzerland captured the sun’s counterglow – or gegenschein – on November 2, 2024, and wrote: “The elusive gegenschein phenomenon captured on a clear night from the Simplon Pass in Switzerland. The antisolar point is located in the top right image, barely visible as a very faint and diffuse nebulosity extending over 20 degrees in a sky with green and orange airglow. The image was highly contrasted to accentuate the phenomenon.” Thank you, Paolo.

Bottom line: Airglow is a light that occurs high in Earth’s atmosphere. It’s usually too dim to see with the eye, but photographers can capture glorious photographs of it.

The post What is airglow? This glowing light is not an aurora first appeared on EarthSky.

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Lyra the Harp contains Vega, a summer gem

This is the constellation Lyra the Harp. It’s made of a triangle and a parallelogram. Its brightest star is Vega. Then, look next to it for Epsilon Lyrae, the famous Double Double star.

Lyra is the 52nd smallest of the 88 constellations, but it has a big presence. That’s because its brightest star Vega is the 5th brightest star in Earth’s sky, or the 2nd brightest star belonging to just the Northern Hemisphere. Vega is best known for being the corner of the famous Summer Triangle star pattern.

Lyra is described as a harp, lyre or stringed instrument. And it’s one of the constellations that Ptolemy named back in the 2nd century.

How to find Lyra in the Northern Hemisphere

The easiest way to find Lyra is to look directly overhead on summer evenings in the Northern Hemisphere. The brightest star closest to your zenith – directly overhead – on a summer night after the sky gets dark will be Vega. It will get closer to the zenith and pass through it as the evening turns to morning.

Here are the 3 stars of the Summer Triangle, in the east in the evening in June and July. You can see the outline of Vega’s constellation, Lyra. Look for the Summer Triangle in the evening from around May through the end of the year.

How to find Lyra in the Southern Hemisphere

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

Although Lyra is often described as a Northern Hemisphere summer constellation, it is also visible throughout much of the Southern Hemisphere during winter.

The altitude of its brightest star, Vega, depends strongly on latitude. It reaches about 39 degrees above the northern horizon from Darwin, 24 degrees from Brisbane, 17 degrees from Sydney, 13 degrees from Melbourne, and only 8 degrees from Christchurch. For reference, a fist at arm’s length covers about 10 degrees on the sky.

One of the most noticeable differences for Southern Hemisphere observers is Lyra’s orientation. Unlike the view shown in many Northern Hemisphere star charts, Vega is the lowest of Lyra’s bright stars when the constellation reaches its highest in the sky, with the rest of the harp-shaped pattern sitting higher above it. This gives Lyra a distinctly different appearance from our perspective, with the highest star being Sulafat, about 6 degrees higher than Vega.

This also places the famous Ring Nebula or M57 (more on that later) above Vega in our sky. That makes it easier to locate, despite Lyra’s generally low altitude in southern latitudes. At these elevations, the Ring Nebula can sit high enough above the denser, murkier layers of the atmosphere that it remains a viable and rewarding telescopic target.

A hotbed of double stars

Once you find Vega, wait until your eyes are dark-adjusted so that you can make out the parallelogram dangling below it if you’re in the Northern Hemisphere, or above it if you’re in the Southern Hemisphere. Then, when you look back toward Vega, can you trace out a small triangle shape attached to the parallelogram? That star making up the small triangle, and which is not part of the parallelogram, is Epsilon Lyrae. And this star holds a secret.

Epsilon Lyrae is more famously known as the Double Double. Through binoculars, this star appears as two stars. But a telescope reveals that each of these is actually another pair of stars, making a quadruple system. And in the mid-1980s, astronomers detected a 5th star in Epsilon Lyrae! This deceptive star system lies about 160 light-years away.

Now that we’ve met Vega (Alpha Lyrae) and Epsilon Lyrae, let’s meet the other stars in the Harp. The two stars in the parallelogram closest to Vega are the dimmer of the four stars. These two stars are both double stars. The double star directly below Vega is Zeta Lyrae. The stars in this pair have magnitudes 4.34 and 5.73. They lie just 44 arcseconds from each other and 150 light-years away from us. A telescope can easily split the pair, but a good pair of binoculars may work as well.

The next double star in the parallelogram consists of Delta 1 and 2 Lyrae. The brighter star has magnitude 4.22, and the dimmer is of magnitude 5.58. They lie 10 arcminutes from each other, so you can easily split them in binoculars. The Delta 1 and 2 stars lie 1,080 and 898 light-years away, respectively.

This is a telescopic view of Epsilon Lyrae, the Double Double star in the constellation Lyra the Harp. To the unaided eye, this is a single star. See how a zoomed-in view splits it into 2 stars, and each of those into 2 again? Image via Nikolay Nikolov/ Wikimedia Commons.

The rest of the stars of the Harp

Next, continuing on down to the bottom of the parallelogram, we find the stars Beta Lyrae, or Sheliak, and Sulafat, or Gamma Lyrae. Sulafat is the star farthest from Vega. It shines at magnitude 3.25 at a distance of 635 light-years. Sheliak is the last star in the parallelogram and – surprise! – it is also a double star. The main star has a magnitude of 3.52 and its companion is of magnitude 7.14. You can split this eclipsing binary in large telescopes.

The stars of Lyra. Vega is represented by the large black circle, indicating its brightness relative to other stars. Image via IAU/ Sky & Telescope/ Wikimedia Commons.

Deep-sky objects in Lyra

Two Messier objects reside in Lyra. The first is a famous planetary nebula known as the Ring Nebula, or M57. Without a doubt, it’s one of the most observed objects of its type in the sky. It shines at magnitude 9.0 from about 2,300 light-years away. And it’s easy to find by looking between the stars Sheliak and Sulafat, at the end of the parallelogram opposite Vega. Use a telescope to catch its beautiful, eerie oval glow.

View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, and Southold, New York, captured this telescopic view of the Ring Nebula on June 23, 2025. Thank you, Steven!

Then a little more than halfway between Sulafat and Albireo, the bright double star at the end of Cygnus, you’ll find M56, a loose globular cluster. M56 is an immense ball of stars orbiting the Milky Way, lying almost 33,000 light-years away.

M56 is a globular cluster in Lyra. Image via Hunter Wilson/ Wikimedia Commons.

Bottom line: The constellation Lyra the Harp hosts the second brightest star in the northern sky, Vega. Look for it on northern summer nights.

Read more: Apex of the sun: Look to Vega in May

The post Lyra the Harp contains Vega, a summer gem first appeared on EarthSky.

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This is the constellation Lyra the Harp. It’s made of a triangle and a parallelogram. Its brightest star is Vega. Then, look next to it for Epsilon Lyrae, the famous Double Double star.

Lyra is the 52nd smallest of the 88 constellations, but it has a big presence. That’s because its brightest star Vega is the 5th brightest star in Earth’s sky, or the 2nd brightest star belonging to just the Northern Hemisphere. Vega is best known for being the corner of the famous Summer Triangle star pattern.

Lyra is described as a harp, lyre or stringed instrument. And it’s one of the constellations that Ptolemy named back in the 2nd century.

How to find Lyra in the Northern Hemisphere

The easiest way to find Lyra is to look directly overhead on summer evenings in the Northern Hemisphere. The brightest star closest to your zenith – directly overhead – on a summer night after the sky gets dark will be Vega. It will get closer to the zenith and pass through it as the evening turns to morning.

Here are the 3 stars of the Summer Triangle, in the east in the evening in June and July. You can see the outline of Vega’s constellation, Lyra. Look for the Summer Triangle in the evening from around May through the end of the year.

How to find Lyra in the Southern Hemisphere

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

Although Lyra is often described as a Northern Hemisphere summer constellation, it is also visible throughout much of the Southern Hemisphere during winter.

The altitude of its brightest star, Vega, depends strongly on latitude. It reaches about 39 degrees above the northern horizon from Darwin, 24 degrees from Brisbane, 17 degrees from Sydney, 13 degrees from Melbourne, and only 8 degrees from Christchurch. For reference, a fist at arm’s length covers about 10 degrees on the sky.

One of the most noticeable differences for Southern Hemisphere observers is Lyra’s orientation. Unlike the view shown in many Northern Hemisphere star charts, Vega is the lowest of Lyra’s bright stars when the constellation reaches its highest in the sky, with the rest of the harp-shaped pattern sitting higher above it. This gives Lyra a distinctly different appearance from our perspective, with the highest star being Sulafat, about 6 degrees higher than Vega.

This also places the famous Ring Nebula or M57 (more on that later) above Vega in our sky. That makes it easier to locate, despite Lyra’s generally low altitude in southern latitudes. At these elevations, the Ring Nebula can sit high enough above the denser, murkier layers of the atmosphere that it remains a viable and rewarding telescopic target.

A hotbed of double stars

Once you find Vega, wait until your eyes are dark-adjusted so that you can make out the parallelogram dangling below it if you’re in the Northern Hemisphere, or above it if you’re in the Southern Hemisphere. Then, when you look back toward Vega, can you trace out a small triangle shape attached to the parallelogram? That star making up the small triangle, and which is not part of the parallelogram, is Epsilon Lyrae. And this star holds a secret.

Epsilon Lyrae is more famously known as the Double Double. Through binoculars, this star appears as two stars. But a telescope reveals that each of these is actually another pair of stars, making a quadruple system. And in the mid-1980s, astronomers detected a 5th star in Epsilon Lyrae! This deceptive star system lies about 160 light-years away.

Now that we’ve met Vega (Alpha Lyrae) and Epsilon Lyrae, let’s meet the other stars in the Harp. The two stars in the parallelogram closest to Vega are the dimmer of the four stars. These two stars are both double stars. The double star directly below Vega is Zeta Lyrae. The stars in this pair have magnitudes 4.34 and 5.73. They lie just 44 arcseconds from each other and 150 light-years away from us. A telescope can easily split the pair, but a good pair of binoculars may work as well.

The next double star in the parallelogram consists of Delta 1 and 2 Lyrae. The brighter star has magnitude 4.22, and the dimmer is of magnitude 5.58. They lie 10 arcminutes from each other, so you can easily split them in binoculars. The Delta 1 and 2 stars lie 1,080 and 898 light-years away, respectively.

This is a telescopic view of Epsilon Lyrae, the Double Double star in the constellation Lyra the Harp. To the unaided eye, this is a single star. See how a zoomed-in view splits it into 2 stars, and each of those into 2 again? Image via Nikolay Nikolov/ Wikimedia Commons.

The rest of the stars of the Harp

Next, continuing on down to the bottom of the parallelogram, we find the stars Beta Lyrae, or Sheliak, and Sulafat, or Gamma Lyrae. Sulafat is the star farthest from Vega. It shines at magnitude 3.25 at a distance of 635 light-years. Sheliak is the last star in the parallelogram and – surprise! – it is also a double star. The main star has a magnitude of 3.52 and its companion is of magnitude 7.14. You can split this eclipsing binary in large telescopes.

The stars of Lyra. Vega is represented by the large black circle, indicating its brightness relative to other stars. Image via IAU/ Sky & Telescope/ Wikimedia Commons.

Deep-sky objects in Lyra

Two Messier objects reside in Lyra. The first is a famous planetary nebula known as the Ring Nebula, or M57. Without a doubt, it’s one of the most observed objects of its type in the sky. It shines at magnitude 9.0 from about 2,300 light-years away. And it’s easy to find by looking between the stars Sheliak and Sulafat, at the end of the parallelogram opposite Vega. Use a telescope to catch its beautiful, eerie oval glow.

View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, and Southold, New York, captured this telescopic view of the Ring Nebula on June 23, 2025. Thank you, Steven!

Then a little more than halfway between Sulafat and Albireo, the bright double star at the end of Cygnus, you’ll find M56, a loose globular cluster. M56 is an immense ball of stars orbiting the Milky Way, lying almost 33,000 light-years away.

M56 is a globular cluster in Lyra. Image via Hunter Wilson/ Wikimedia Commons.

Bottom line: The constellation Lyra the Harp hosts the second brightest star in the northern sky, Vega. Look for it on northern summer nights.

Read more: Apex of the sun: Look to Vega in May

The post Lyra the Harp contains Vega, a summer gem first appeared on EarthSky.

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Comet 3I/ATLAS has methane, unexpected discovery reveals

View larger/ full image. | This image of Comet 3I/ATLAS shows the interstellar comet shining against a background of stars. The European Space Agency’s JUICE spacecraft obtained this image and other data on November 6, 2025. New analysis of data from the James Webb Space Telescope shows that Comet 3I/ATLAS has methane, and a lot of it. Image via ESA/ Juice/ JANUS.

• Comet 3I/ATLAS is the 3rd known interstellar object to enter our solar system. We are still learning about its composition.
• New analysis of data from the James Webb Space Telescope reveals that it contains abundant methane.
• It’s the first time that methane has been found on an interstellar object. The findings suggest that the environment the comet formed in was quite different from that of our solar system.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Surprise! Comet 3I/ATLAS has methane

NASA’s James Webb Space Telescope has made another significant discovery about the interstellar comet 3I/ATLAS: it contains methane.

Researchers said on June 1, 2026, that this is the 1st time scientists have detected methane on an interstellar object. And the finding suggests 3I/ATLAS was born in a very different environment from that of our solar system.

The team of researchers made the discovery after using the Webb space telescope to observe the comet as it headed back out of the solar system in December 2025. The fact that methane wasn’t detected as the comet sped into the solar system suggests the gas was buried below the top surface of ice. So it was only detectable when the ice and frozen methane sublimated – turned directly to gas – as the comet came close to the sun.

The researchers published their new peer-reviewed findings in The Astrophysical Journal Letters on April 8, 2026.

1st detection of methane on an interstellar object hints at comet’s origin

So this is the 1st time that scientists have found methane on an interstellar object. Mind you, 3I/ATLAS is only the 3rd of these objects we’ve identified. The 1st discovery was the enigmatic comet ‘Oumuamua, and the 2nd was the comet 2I/Borisov.

The researchers also found that Comet 3I/ATLAS is oddly rich in carbon dioxide. And this abundance of carbon dioxide and methane provides clues to the comet’s origin.

Comets in our solar system don’t contain large amounts of these gases. This means that 3I/ATLAS must have been born in a very different environment and chemistry than that of our solar system.

View larger. | Chart depicting the various gases that Webb found on Comet 3I/ATLAS. Methane and carbon dioxide are the most common, concentrated near the comet’s nucleus. Image via NASA/ ESA/ CSA/ STScI/ M. Belyakov (Caltech)/ I. Wong (STScI), Image Processing: A. Pagan (STScI).

Why the delay in detecting the methane?

Scientists first spotted Comet 3I/ATLAS in July, 2025, and it passed closest to the sun in October. But they didn’t detect the methane until the comet was on its way out of the solar system in December. Why is that?

The researchers say it’s likely because the methane was buried under a significant amount of surface ice. It wasn’t until the comet swung closest to the sun during its departure that the comet warmed enough for the methane to sublimate. Sublimation is when a frozen substance turns directly into a gas instead of becoming liquid first.

Comet 3I/ATLAS through red and violet filters. In the red filter, the bright center of the coma is more compact and there are two tails: one straight down, and a fuzzier one going to the lower left. In the violet filter, the coma is bigger but fainter, and only one tail stands out clearly. The differences arise because different gas and dust particles release or reflect light at different wavelengths. Image via ESA.

Other recent 3I/ATLAS news

SETI also recently scanned 3I/ATLAS for possible radio signals. It was a last chance to see if – by any chance – the comet might actually be an artificial object. But alas, nothing was found.

Another study from April found that Comet 3I/ATLAS formed in a cold environment. This is consistent with the newest findings.

And in March, scientists found that 3I/ATLAS is bursting with alcohol, or methanol to be specific.

Bottom line: New analysis of data from the Webb space telescope shows that Comet 3I/ATLAS has methane. This shows its origin is different from comets in our solar system.

Source: The Volatile Inventory of 3I/ATLAS as Seen with JWST/MIRI

Via NASA

Read more: Interstellar comet 3I/ATLAS born in a cold environment

Read more: Interstellar object Comet 3I/ATLAS leaving the solar system

The post Comet 3I/ATLAS has methane, unexpected discovery reveals first appeared on EarthSky.

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View larger/ full image. | This image of Comet 3I/ATLAS shows the interstellar comet shining against a background of stars. The European Space Agency’s JUICE spacecraft obtained this image and other data on November 6, 2025. New analysis of data from the James Webb Space Telescope shows that Comet 3I/ATLAS has methane, and a lot of it. Image via ESA/ Juice/ JANUS.

• Comet 3I/ATLAS is the 3rd known interstellar object to enter our solar system. We are still learning about its composition.
• New analysis of data from the James Webb Space Telescope reveals that it contains abundant methane.
• It’s the first time that methane has been found on an interstellar object. The findings suggest that the environment the comet formed in was quite different from that of our solar system.

Science news, night sky events and beautiful photos, all in one place. Click here to subscribe to our free daily newsletter.

Surprise! Comet 3I/ATLAS has methane

NASA’s James Webb Space Telescope has made another significant discovery about the interstellar comet 3I/ATLAS: it contains methane.

Researchers said on June 1, 2026, that this is the 1st time scientists have detected methane on an interstellar object. And the finding suggests 3I/ATLAS was born in a very different environment from that of our solar system.

The team of researchers made the discovery after using the Webb space telescope to observe the comet as it headed back out of the solar system in December 2025. The fact that methane wasn’t detected as the comet sped into the solar system suggests the gas was buried below the top surface of ice. So it was only detectable when the ice and frozen methane sublimated – turned directly to gas – as the comet came close to the sun.

The researchers published their new peer-reviewed findings in The Astrophysical Journal Letters on April 8, 2026.

1st detection of methane on an interstellar object hints at comet’s origin

So this is the 1st time that scientists have found methane on an interstellar object. Mind you, 3I/ATLAS is only the 3rd of these objects we’ve identified. The 1st discovery was the enigmatic comet ‘Oumuamua, and the 2nd was the comet 2I/Borisov.

The researchers also found that Comet 3I/ATLAS is oddly rich in carbon dioxide. And this abundance of carbon dioxide and methane provides clues to the comet’s origin.

Comets in our solar system don’t contain large amounts of these gases. This means that 3I/ATLAS must have been born in a very different environment and chemistry than that of our solar system.

View larger. | Chart depicting the various gases that Webb found on Comet 3I/ATLAS. Methane and carbon dioxide are the most common, concentrated near the comet’s nucleus. Image via NASA/ ESA/ CSA/ STScI/ M. Belyakov (Caltech)/ I. Wong (STScI), Image Processing: A. Pagan (STScI).

Why the delay in detecting the methane?

Scientists first spotted Comet 3I/ATLAS in July, 2025, and it passed closest to the sun in October. But they didn’t detect the methane until the comet was on its way out of the solar system in December. Why is that?

The researchers say it’s likely because the methane was buried under a significant amount of surface ice. It wasn’t until the comet swung closest to the sun during its departure that the comet warmed enough for the methane to sublimate. Sublimation is when a frozen substance turns directly into a gas instead of becoming liquid first.

Comet 3I/ATLAS through red and violet filters. In the red filter, the bright center of the coma is more compact and there are two tails: one straight down, and a fuzzier one going to the lower left. In the violet filter, the coma is bigger but fainter, and only one tail stands out clearly. The differences arise because different gas and dust particles release or reflect light at different wavelengths. Image via ESA.

Other recent 3I/ATLAS news

SETI also recently scanned 3I/ATLAS for possible radio signals. It was a last chance to see if – by any chance – the comet might actually be an artificial object. But alas, nothing was found.

Another study from April found that Comet 3I/ATLAS formed in a cold environment. This is consistent with the newest findings.

And in March, scientists found that 3I/ATLAS is bursting with alcohol, or methanol to be specific.

Bottom line: New analysis of data from the Webb space telescope shows that Comet 3I/ATLAS has methane. This shows its origin is different from comets in our solar system.

Source: The Volatile Inventory of 3I/ATLAS as Seen with JWST/MIRI

Via NASA

Read more: Interstellar comet 3I/ATLAS born in a cold environment

Read more: Interstellar object Comet 3I/ATLAS leaving the solar system

The post Comet 3I/ATLAS has methane, unexpected discovery reveals first appeared on EarthSky.

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