Pluto demoted to dwarf planet 20 years ago today

Pluto backlit, via New Horizons spacecraft on July 14, 2015. Image via NASA/ JHUAPL/ SwRI.

Dwarf planet Pluto

On August 24, 2006, the International Astronomical Union (IAU) announced it had re-classified Pluto as a dwarf planet. From 1930 until that day, Pluto had been considered a normal planet, and the outermost world of the solar system. As technology advanced, though, astronomers began to see fainter and fainter objects in our neighborhood. That led them to recognize Pluto as only the largest of many small bodies in the outer solar system.

Now Pluto is known as a dwarf planet, and Neptune – 8th world from the sun – is considered the outermost major planet. It all came about because the IAU had formulated a new definition of what it means to be a planet.

The public and even some astronomers didn’t initially take it lightly. Some declared they would still consider Pluto a planet. The word ‘plutoed‘ – meaning to demote or devalue something – entered the global lexicon. Nowadays, though, it seems most have accepted the logic of Pluto’s re-classification… or, at least, we don’t hear as much of an uproar about it as we used to.

Why did Pluto change status?

Prior to 2006, astronomers hadn’t gotten around to establishing clear standards for categorizing a solar system “planet” versus a “dwarf planet.”

They began to see a need when many small bodies – such as Haumea and Makemake – began to be discovered in the outer solar system. Eris, also considered a dwarf planet, has even more mass than Pluto (though it’s not quite as large). So if Pluto is a planet, why shouldn’t Eris be granted planet status as well? That was the question the IAU asked itself, which led to its formation of a Planet Definition Committee and ultimately the 2006 decision.

The committee had a few possible roads to travel down. One would be to choose a size or mass limit that would make Pluto remain a planet. That would mean that Eris and Ceres – the largest body in the inner solar system’s asteroid belt – would become planets, too. This was the solution of some IAU committee members, and it looked like it might be implemented for a while.

Another option for the IAU might have been to define the concept of a planet without any specific logic: Earth is a planet, Pluto is a planet, but Eris is not just because. But would that have been very scientific?

Meet the The Planet Definition Committee of the International Astronomical Union. This group made the final decision to “demote” Pluto to dwarf planet status. But, even within the committee, not all initially agreed. Image via IAU.

New planetary classifications

On August 24, 2006, the IAU announced its solution. It decided to create a scientific definition of what it means to be a planet. And that definition excluded Pluto from major planet status. Here’s the definition:

A planet is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighborhood around its orbit.

It’s “c” that causes Pluto to fail as a planet, according to the IAU. For an object to be a major planet, according to this definition, it must be the dominant gravitational object in its orbit. It must either sling other objects away or merge with them.

Pluto is only 0.07 times the mass of the objects in its orbit. Meanwhile, Earth is 1.7 million times the mass of the objects in its orbit.

When Pluto lost its full planet status, it was revealed as one of the world’s most beloved astronomical objects. So it was fitting that New Horizons – the first spacecraft ever to visit Pluto – discovered a heart-shaped region on it in 2015. Image taken 280,000 miles (450,000 km) from Pluto, via NASA/ JHUAPL/ SwRI.

Pluto hasn’t cleared its neighborhood

On that fateful day – August 24, 2006 – the IAU also created a new category of celestial objects for Pluto and all Pluto-like objects:

A “dwarf planet” is a celestial body that
(a) is in orbit around the sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(c) has not cleared the neighborhood around its orbit, and
(d) is not a satellite.

How many dwarf planets are there? According to this page by planetary astronomer Mike Brown of CalTech, as of November 25, 2025, there are:

10 objects which are nearly certainly dwarf planets,
27 objects which are highly likely to be dwarf planets,
68 objects which are likely to be dwarf planets,
130 objects which are probably dwarf planets, and
741 objects which are possibly dwarf planets.

New Horizons captured this image just 15 minutes after its closest approach to Pluto on July 14, 2015, as the spacecraft looked back toward the sun. This near-sunset view shows Pluto’s rugged, icy mountains and flat ice plains, plus haze layers in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 km); the scene is 780 miles (1,250 km) wide. Image via NASA/ JHUAPL/ SwRI.

Hundreds of dwarf planets?

Astronomers believe there may be hundreds more undiscovered dwarf planets in the Kuiper Belt of the outer solar system. There may be up to 10,000 in the region beyond.

More about the Kuiper Belt: https://t.co/qNCG1GvgeP https://t.co/kPGvZtR4IY pic.twitter.com/FYX5Cv2PDD

— NASA Solar System (@NASASolarSystem) February 20, 2024

Not a new idea

By the way, it’s not common knowledge that many astronomers started out being quite careful about their use of the word “planet” with respect to Pluto. In 1932, for example, only two years after American astronomer Clyde Tombaugh discovered Pluto, another astronomer, Armin Otto Leuschner, wrote in a journal article:

You may observe that with extreme conservatism I am still referring to Pluto as an object rather than as a planet. There is every probability that it is a planet, as is now universally concluded, from available material … So far only an upper limit for the mass of Pluto … has been established, and such a mass is believed from gravitational considerations to be too small to affect the motions of Uranus and Neptune sufficiently … There is also a remote chance that later investigations will render its mass comparable to that of comets.

Pluto might never have been called a planet at all

Recall why astronomers began searching for Pluto in the first place. They expected to find an object large enough to gravitationally disturb the orbit of Neptune. If Pluto had been discovered a decade or so later, when Edgeworth speculated about the existence of the Kuiper Belt, it might have never been awarded the status of planet.

As it was, like it or not, Pluto became the world’s eye-opener when it came to the classification of solar system objects.

Bottom line: August 24 is the anniversary of Pluto’s demotion to dwarf planet status. The International Astronomical Union demoted Pluto largely because it is has not “cleared the neighborhood around its orbit.”

Read more about Pluto here

The IAU talks about its decision to demote Pluto here

Read more: Pluto terrain in rainbow colors

The post Pluto demoted to dwarf planet 20 years ago today first appeared on EarthSky.

from EarthSky https://ift.tt/1TvH0wb

Pluto backlit, via New Horizons spacecraft on July 14, 2015. Image via NASA/ JHUAPL/ SwRI.

Dwarf planet Pluto

On August 24, 2006, the International Astronomical Union (IAU) announced it had re-classified Pluto as a dwarf planet. From 1930 until that day, Pluto had been considered a normal planet, and the outermost world of the solar system. As technology advanced, though, astronomers began to see fainter and fainter objects in our neighborhood. That led them to recognize Pluto as only the largest of many small bodies in the outer solar system.

Now Pluto is known as a dwarf planet, and Neptune – 8th world from the sun – is considered the outermost major planet. It all came about because the IAU had formulated a new definition of what it means to be a planet.

The public and even some astronomers didn’t initially take it lightly. Some declared they would still consider Pluto a planet. The word ‘plutoed‘ – meaning to demote or devalue something – entered the global lexicon. Nowadays, though, it seems most have accepted the logic of Pluto’s re-classification… or, at least, we don’t hear as much of an uproar about it as we used to.

Why did Pluto change status?

Prior to 2006, astronomers hadn’t gotten around to establishing clear standards for categorizing a solar system “planet” versus a “dwarf planet.”

They began to see a need when many small bodies – such as Haumea and Makemake – began to be discovered in the outer solar system. Eris, also considered a dwarf planet, has even more mass than Pluto (though it’s not quite as large). So if Pluto is a planet, why shouldn’t Eris be granted planet status as well? That was the question the IAU asked itself, which led to its formation of a Planet Definition Committee and ultimately the 2006 decision.

The committee had a few possible roads to travel down. One would be to choose a size or mass limit that would make Pluto remain a planet. That would mean that Eris and Ceres – the largest body in the inner solar system’s asteroid belt – would become planets, too. This was the solution of some IAU committee members, and it looked like it might be implemented for a while.

Another option for the IAU might have been to define the concept of a planet without any specific logic: Earth is a planet, Pluto is a planet, but Eris is not just because. But would that have been very scientific?

Meet the The Planet Definition Committee of the International Astronomical Union. This group made the final decision to “demote” Pluto to dwarf planet status. But, even within the committee, not all initially agreed. Image via IAU.

New planetary classifications

On August 24, 2006, the IAU announced its solution. It decided to create a scientific definition of what it means to be a planet. And that definition excluded Pluto from major planet status. Here’s the definition:

A planet is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighborhood around its orbit.

It’s “c” that causes Pluto to fail as a planet, according to the IAU. For an object to be a major planet, according to this definition, it must be the dominant gravitational object in its orbit. It must either sling other objects away or merge with them.

Pluto is only 0.07 times the mass of the objects in its orbit. Meanwhile, Earth is 1.7 million times the mass of the objects in its orbit.

When Pluto lost its full planet status, it was revealed as one of the world’s most beloved astronomical objects. So it was fitting that New Horizons – the first spacecraft ever to visit Pluto – discovered a heart-shaped region on it in 2015. Image taken 280,000 miles (450,000 km) from Pluto, via NASA/ JHUAPL/ SwRI.

Pluto hasn’t cleared its neighborhood

On that fateful day – August 24, 2006 – the IAU also created a new category of celestial objects for Pluto and all Pluto-like objects:

A “dwarf planet” is a celestial body that
(a) is in orbit around the sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(c) has not cleared the neighborhood around its orbit, and
(d) is not a satellite.

How many dwarf planets are there? According to this page by planetary astronomer Mike Brown of CalTech, as of November 25, 2025, there are:

10 objects which are nearly certainly dwarf planets,
27 objects which are highly likely to be dwarf planets,
68 objects which are likely to be dwarf planets,
130 objects which are probably dwarf planets, and
741 objects which are possibly dwarf planets.

New Horizons captured this image just 15 minutes after its closest approach to Pluto on July 14, 2015, as the spacecraft looked back toward the sun. This near-sunset view shows Pluto’s rugged, icy mountains and flat ice plains, plus haze layers in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 km); the scene is 780 miles (1,250 km) wide. Image via NASA/ JHUAPL/ SwRI.

Hundreds of dwarf planets?

Astronomers believe there may be hundreds more undiscovered dwarf planets in the Kuiper Belt of the outer solar system. There may be up to 10,000 in the region beyond.

More about the Kuiper Belt: https://t.co/qNCG1GvgeP https://t.co/kPGvZtR4IY pic.twitter.com/FYX5Cv2PDD

— NASA Solar System (@NASASolarSystem) February 20, 2024

Not a new idea

By the way, it’s not common knowledge that many astronomers started out being quite careful about their use of the word “planet” with respect to Pluto. In 1932, for example, only two years after American astronomer Clyde Tombaugh discovered Pluto, another astronomer, Armin Otto Leuschner, wrote in a journal article:

You may observe that with extreme conservatism I am still referring to Pluto as an object rather than as a planet. There is every probability that it is a planet, as is now universally concluded, from available material … So far only an upper limit for the mass of Pluto … has been established, and such a mass is believed from gravitational considerations to be too small to affect the motions of Uranus and Neptune sufficiently … There is also a remote chance that later investigations will render its mass comparable to that of comets.

Pluto might never have been called a planet at all

Recall why astronomers began searching for Pluto in the first place. They expected to find an object large enough to gravitationally disturb the orbit of Neptune. If Pluto had been discovered a decade or so later, when Edgeworth speculated about the existence of the Kuiper Belt, it might have never been awarded the status of planet.

As it was, like it or not, Pluto became the world’s eye-opener when it came to the classification of solar system objects.

Bottom line: August 24 is the anniversary of Pluto’s demotion to dwarf planet status. The International Astronomical Union demoted Pluto largely because it is has not “cleared the neighborhood around its orbit.”

Read more about Pluto here

The IAU talks about its decision to demote Pluto here

Read more: Pluto terrain in rainbow colors

The post Pluto demoted to dwarf planet 20 years ago today first appeared on EarthSky.

from EarthSky https://ift.tt/1TvH0wb

1st photo of Earth from the moon 60 years ago

Lunar Orbiter 1 captured this 1st photo of Earth from the moon on August 23, 1966. See a version of this image restored with modern photographic techniques, below. Image via NASA/Lunar Orbiter 1.

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1st photo of Earth from the moon

On August 23, 1966, Lunar Orbiter 1 took the 1st-ever photo of the Earth from the moon. It shows half of Earth, shot with 1960s technology, seen from the moon’s distance of 236,000 miles (380,000 km). And in the image, you can see the Earth from Istanbul to Cape Town with areas east shrouded in night. The image isn’t very detailed. But it’s mind-boggling to think about. What a contrast with NASA’s recent Artemis 2 mission that sent astronauts to orbit the moon for the first time in over 50 years! See Artemis 2 images here.

Lunar Orbiter 1 was one of five Lunar Orbiters that NASA sent to the moon in the 1960s. The Lunar Orbiter’s priority was to take photographs of the moon. That’s because NASA was preparing for the first manned Apollo mission, which came three years later. Read about the Lunar Orbiter missions, 1966-1967.

As you can see, the photo taken in 1966 reveals no detail on Earth’s surface.

But, surely, this photo stunned those on Earth who finally saw our home planet from the moon.

Years later, a digitally enhanced version

Then, in 2008, NASA released a newly restored version of the original 1966 image of Earth. NASA used refurbished machinery and modern digital technology. Consequently, the new image is higher resolution than what was possible when it was originally taken. Wow! What a difference.

The impressive restored image of the Earth from the moon is below.

In 2008, NASA restored this 1st image of Earth from the moon. Lunar Orbiter 1 took the original image. NASA used photographic techniques that were not available when that early spacecraft originally acquired this historic photo. Read more about this photo from NASA.

Bottom line: As NASA plans to land astronauts on the moon with the Artemis IV mission in 2028, it’s fun to see this 1st-ever photo of Earth from the moon, taken on August 23, 1966.

NASA releases 12,000 Artemis pics! See our faves here

The post 1st photo of Earth from the moon 60 years ago first appeared on EarthSky.

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Lunar Orbiter 1 captured this 1st photo of Earth from the moon on August 23, 1966. See a version of this image restored with modern photographic techniques, below. Image via NASA/Lunar Orbiter 1.

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

1st photo of Earth from the moon

On August 23, 1966, Lunar Orbiter 1 took the 1st-ever photo of the Earth from the moon. It shows half of Earth, shot with 1960s technology, seen from the moon’s distance of 236,000 miles (380,000 km). And in the image, you can see the Earth from Istanbul to Cape Town with areas east shrouded in night. The image isn’t very detailed. But it’s mind-boggling to think about. What a contrast with NASA’s recent Artemis 2 mission that sent astronauts to orbit the moon for the first time in over 50 years! See Artemis 2 images here.

Lunar Orbiter 1 was one of five Lunar Orbiters that NASA sent to the moon in the 1960s. The Lunar Orbiter’s priority was to take photographs of the moon. That’s because NASA was preparing for the first manned Apollo mission, which came three years later. Read about the Lunar Orbiter missions, 1966-1967.

As you can see, the photo taken in 1966 reveals no detail on Earth’s surface.

But, surely, this photo stunned those on Earth who finally saw our home planet from the moon.

Years later, a digitally enhanced version

Then, in 2008, NASA released a newly restored version of the original 1966 image of Earth. NASA used refurbished machinery and modern digital technology. Consequently, the new image is higher resolution than what was possible when it was originally taken. Wow! What a difference.

The impressive restored image of the Earth from the moon is below.

In 2008, NASA restored this 1st image of Earth from the moon. Lunar Orbiter 1 took the original image. NASA used photographic techniques that were not available when that early spacecraft originally acquired this historic photo. Read more about this photo from NASA.

Bottom line: As NASA plans to land astronauts on the moon with the Artemis IV mission in 2028, it’s fun to see this 1st-ever photo of Earth from the moon, taken on August 23, 1966.

NASA releases 12,000 Artemis pics! See our faves here

The post 1st photo of Earth from the moon 60 years ago first appeared on EarthSky.

from EarthSky https://ift.tt/uMa5KOy

Sagittarius the Archer is home to deep-sky wonders

Sagittarius the Archer contains a Teapot shape. It’s located in the direction of the center of our Milky Way galaxy. If you live far enough south – say at least at latitudes like those in the southern U.S., or farther south – you might spot the arcing shape of Corona Australis near Sagittarius. Image via EarthSky.

If you’re outside on an August or September evening, you can glimpse the zodiacal constellation Sagittarius the Archer. From our northerly latitudes, it never climbs high in the sky. Yet when you’re looking toward Sagittarius, you’re looking in the direction of one of the most wondrous places we can imagine: the center of our own Milky Way galaxy.

Plus, Sagittarius is fairly easy to spot if you have a dark sky. Its brightest stars form an asterism in the distinctive shape of a Teapot.

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

How to find Sagittarius

You’ll want a dark, rural location to see and enjoy Sagittarius. In August or September, when you’re outside camping or ending a picnic on a summer evening – any place away from light pollution – simply look up. You’ll notice the starlit band of the Milky Way. It’ll appear as a hazy band stretching all the way across the sky. The haze is really countless stars.

From the Northern Hemisphere, the starlit trail of the Milky Way seems to bulge just before it reaches the southern horizon (from the Southern Hemipshere, this bulge is high in the sky). This bulge marks the approximate location of the Milky Way’s center.

Here’s another way to find Sagittarius. If you’re familiar with the Summer Triangle asterism, draw an imaginary line from the star Deneb and through the star Altair to locate Sagittarius near the horizon. At mid-northern latitudes, the Summer Triangle hangs high in the south to overhead on late summer and autumn evenings.

Deep-sky wonders in the Archer

So Sagittarius points to the heart of our Milky Way galaxy. But we can’t see all the way to the center. Why not? Because it’s so far away, 26,000 light-years. And because of the huge plethora of stars, star clusters, nebulae and dust that block our view.

On the other hand, the stars, star clusters, nebulae and dust are themselves worth viewing! And you don’t need to know what you’re seeing to enjoy them. Just take binoculars with you, next time you know you’ll have access to a dark sky on an August or September evening. Look up! And aim your binoculars along the starry path of the Milky Way.

Here are some deep-sky treasures in Sagittarius: Sagittarius Star Cloud (Messier 24), globular cluster Messier 22, Lagoon Nebula (Messier 8), Trifid Nebula (Messier 20) and Omega Nebula (Messier 17).

Sharp-eyed people can even see these deep-sky objects with the unaided eye. Binoculars let you see them better. And a small telescope would give you a beautiful view.

Modern stargazers have difficulty making out the Centaur in Sagittarius. But the Teapot is easy to see, once you learn to look for it. Find the Teapot, and it’ll help you on your star-hopping adventures to deep-sky marvels.

View at EarthSky Community Photos. | Miguel Sala at the Ruins of Ares Castle in Teruel, Spain, captured this photo of the Milky Way on July 10, 2021. Notice near the center of the photo that he has marked the direction of the star-rich center of our galaxy. When we look in this direction, we’re looking toward a sky crowded with star clusters and nebulae. The famous Teapot in Sagittarius – a visual guide to the galaxy’s center – is also in this direction (and on the left side of this photo). Thank you, Miguel!

Photos of the Teapot

The Teapot is the central region of Sagittarius. Once you’ve learned to trace the Teapot’s shape in the sky, it’ll become easier to spot. Check out the photos below to learn its shape and then try to spot it yourself.

View at EarthSky Community Photos. | Catherine Hyde in Cambria, California, captured this photo of the Milky Way on July 10, 2023. Catherine wrote: “This is the Teapot asterism rising from behind a tree. I’ve heard if you can capture the galactic center (Milky Way) behind it, it looks like steam coming out of the spout. I was surprised by how many deep-sky objects I had captured, so I annotated the image.” Thank you, Catherine!

View at EarthSky Community Photos. | Kannan A in Singapore took this photo on May 20, 2021. Kannan wrote: “Sagittarius may look like a teapot, but he is in fact an archer – and a four-legged one to boot: a centaur, to be specific – half horse, half man. The front of the teapot is the bow he pulls back, the spout is the tip of his arrow he aims westward at Scorpius. The remainder of the teapot are stars marking the centaur’s upper body and pulled-back arm; fainter stars southeastward sketch out his lower horsey half.” Thank you, Kannan!

The stars of Sagittarius

The brightest star in Sagittarius is the star marking the bottom right corner of the teapot, Kaus Australis. Also known as Epsilon Sagittarii, this magnitude 1.8 star lies 143 light-years away.

The next brightest star is at the opposite end of the teapot, the top star in the handle, Nunki. Also known as Sigma Sagittarii, this 2.1-magnitude star shines from a distance of 228 light-years.

Most of the other stars in Sagittarius are of 2nd and 3rd magnitude. The star marking the top of the teapot’s lid is Kaus Borealis, a magnitude 2.82 star lying 77 light-years away. The stars marking the top of the spout are Alnasl, which marks the tip of the spout at magnitude 2.98 and is 96 light-years away, and Kaus Media, which marks the spout’s connection to the pot at magnitude 2.72 and is 306 light-years away. The star at the bottom of the handle where it connects to the pot is Ascella, a magnitude 2.60 star lying 89 light-years away.

The constellation Sagittarius, with the Teapot asterism outlined in green. Chart via IAU/ Wikipedia.

Sagittarius in mythology

The constellations Sagittarius and Centaurus are both supposed to represent a centaur, a creature with the upper torso of a man and the body and legs of a horse. Historically, centaurs might have really been like cowboys, using horses to round up cattle in ancient Greece.

According to Greek myth, the centaurs were the offspring of Ixion and the cloud nymph Nephele. Apparently, Sagittarius’ drawn-out bow and arrow originated from the Mesopotamian archer god. So this constellation might not have always represented the centaur Chiron.

It’s said that the Greeks associated Sagittarius with Crotus the satyr, another type of monstrosity, a man with horse ears and tail and goat legs. Quite possibly, the Romans first identified the constellation Sagittarius with Chiron, the wise and kindly centaur.

Here’s something that distinguishes Sagittarius the Archer from the other 13 constellations of the zodiac. The sun shines in front of this constellation on the December 21 solstice.

Also, the ecliptic – the sun’s yearly pathway in front of the backdrop stars – intersects the galactic equator in Sagittarius.

Sagittarius as depicted in Urania’s Mirror, a set of constellation cards published in London in 1825. Image via Wikimedia.

The constellation versus the sign

In our modern times, the sun passes in front of the constellation Sagittarius from about December 18 to January 20. These dates are off by about a month from what you read on the horoscope page. The sun moves through the sign Sagittarius from about November 21 to December 21.

Yes, there is a difference between an astronomical constellation and an astrological sign! Keep in mind that we’re talking about the constellation Sagittarius in this article. The horoscope is referring to the sign Sagittarius.

By definition, the sun enters the sign Sagittarius whenever the sun is precisely 30 degrees west of the December solstice point. Then, on the December solstice, the sun enters the sign Capricorn.

While the signs remain fixed relative to the solstices and equinoxes, the solstices and equinox points move 30 degrees westward in front of the constellations – or backdrop stars – in about 2,160 years.

The constellation boundaries were formally defined by the International Astronomical Union (IAU) in 1930. Based on the present IAU boundaries, the December solstice point moved into the constellation Sagittarius in the year 131 BCE and will move into the constellation Ophiuchus in 2269 CE.

Bottom line: Look for the constellation Sagittarius on an August or September evening. The brightest stars in Sagittarius form the distinctive shape of a teapot. And the spout of the Teapot points to the center of the Milky Way galaxy.

Teapot of Sagittarius points to the Milky Way’s center

The post Sagittarius the Archer is home to deep-sky wonders first appeared on EarthSky.

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Sagittarius the Archer contains a Teapot shape. It’s located in the direction of the center of our Milky Way galaxy. If you live far enough south – say at least at latitudes like those in the southern U.S., or farther south – you might spot the arcing shape of Corona Australis near Sagittarius. Image via EarthSky.

If you’re outside on an August or September evening, you can glimpse the zodiacal constellation Sagittarius the Archer. From our northerly latitudes, it never climbs high in the sky. Yet when you’re looking toward Sagittarius, you’re looking in the direction of one of the most wondrous places we can imagine: the center of our own Milky Way galaxy.

Plus, Sagittarius is fairly easy to spot if you have a dark sky. Its brightest stars form an asterism in the distinctive shape of a Teapot.

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

How to find Sagittarius

You’ll want a dark, rural location to see and enjoy Sagittarius. In August or September, when you’re outside camping or ending a picnic on a summer evening – any place away from light pollution – simply look up. You’ll notice the starlit band of the Milky Way. It’ll appear as a hazy band stretching all the way across the sky. The haze is really countless stars.

From the Northern Hemisphere, the starlit trail of the Milky Way seems to bulge just before it reaches the southern horizon (from the Southern Hemipshere, this bulge is high in the sky). This bulge marks the approximate location of the Milky Way’s center.

Here’s another way to find Sagittarius. If you’re familiar with the Summer Triangle asterism, draw an imaginary line from the star Deneb and through the star Altair to locate Sagittarius near the horizon. At mid-northern latitudes, the Summer Triangle hangs high in the south to overhead on late summer and autumn evenings.

Deep-sky wonders in the Archer

So Sagittarius points to the heart of our Milky Way galaxy. But we can’t see all the way to the center. Why not? Because it’s so far away, 26,000 light-years. And because of the huge plethora of stars, star clusters, nebulae and dust that block our view.

On the other hand, the stars, star clusters, nebulae and dust are themselves worth viewing! And you don’t need to know what you’re seeing to enjoy them. Just take binoculars with you, next time you know you’ll have access to a dark sky on an August or September evening. Look up! And aim your binoculars along the starry path of the Milky Way.

Here are some deep-sky treasures in Sagittarius: Sagittarius Star Cloud (Messier 24), globular cluster Messier 22, Lagoon Nebula (Messier 8), Trifid Nebula (Messier 20) and Omega Nebula (Messier 17).

Sharp-eyed people can even see these deep-sky objects with the unaided eye. Binoculars let you see them better. And a small telescope would give you a beautiful view.

Modern stargazers have difficulty making out the Centaur in Sagittarius. But the Teapot is easy to see, once you learn to look for it. Find the Teapot, and it’ll help you on your star-hopping adventures to deep-sky marvels.

View at EarthSky Community Photos. | Miguel Sala at the Ruins of Ares Castle in Teruel, Spain, captured this photo of the Milky Way on July 10, 2021. Notice near the center of the photo that he has marked the direction of the star-rich center of our galaxy. When we look in this direction, we’re looking toward a sky crowded with star clusters and nebulae. The famous Teapot in Sagittarius – a visual guide to the galaxy’s center – is also in this direction (and on the left side of this photo). Thank you, Miguel!

Photos of the Teapot

The Teapot is the central region of Sagittarius. Once you’ve learned to trace the Teapot’s shape in the sky, it’ll become easier to spot. Check out the photos below to learn its shape and then try to spot it yourself.

View at EarthSky Community Photos. | Catherine Hyde in Cambria, California, captured this photo of the Milky Way on July 10, 2023. Catherine wrote: “This is the Teapot asterism rising from behind a tree. I’ve heard if you can capture the galactic center (Milky Way) behind it, it looks like steam coming out of the spout. I was surprised by how many deep-sky objects I had captured, so I annotated the image.” Thank you, Catherine!

View at EarthSky Community Photos. | Kannan A in Singapore took this photo on May 20, 2021. Kannan wrote: “Sagittarius may look like a teapot, but he is in fact an archer – and a four-legged one to boot: a centaur, to be specific – half horse, half man. The front of the teapot is the bow he pulls back, the spout is the tip of his arrow he aims westward at Scorpius. The remainder of the teapot are stars marking the centaur’s upper body and pulled-back arm; fainter stars southeastward sketch out his lower horsey half.” Thank you, Kannan!

The stars of Sagittarius

The brightest star in Sagittarius is the star marking the bottom right corner of the teapot, Kaus Australis. Also known as Epsilon Sagittarii, this magnitude 1.8 star lies 143 light-years away.

The next brightest star is at the opposite end of the teapot, the top star in the handle, Nunki. Also known as Sigma Sagittarii, this 2.1-magnitude star shines from a distance of 228 light-years.

Most of the other stars in Sagittarius are of 2nd and 3rd magnitude. The star marking the top of the teapot’s lid is Kaus Borealis, a magnitude 2.82 star lying 77 light-years away. The stars marking the top of the spout are Alnasl, which marks the tip of the spout at magnitude 2.98 and is 96 light-years away, and Kaus Media, which marks the spout’s connection to the pot at magnitude 2.72 and is 306 light-years away. The star at the bottom of the handle where it connects to the pot is Ascella, a magnitude 2.60 star lying 89 light-years away.

The constellation Sagittarius, with the Teapot asterism outlined in green. Chart via IAU/ Wikipedia.

Sagittarius in mythology

The constellations Sagittarius and Centaurus are both supposed to represent a centaur, a creature with the upper torso of a man and the body and legs of a horse. Historically, centaurs might have really been like cowboys, using horses to round up cattle in ancient Greece.

According to Greek myth, the centaurs were the offspring of Ixion and the cloud nymph Nephele. Apparently, Sagittarius’ drawn-out bow and arrow originated from the Mesopotamian archer god. So this constellation might not have always represented the centaur Chiron.

It’s said that the Greeks associated Sagittarius with Crotus the satyr, another type of monstrosity, a man with horse ears and tail and goat legs. Quite possibly, the Romans first identified the constellation Sagittarius with Chiron, the wise and kindly centaur.

Here’s something that distinguishes Sagittarius the Archer from the other 13 constellations of the zodiac. The sun shines in front of this constellation on the December 21 solstice.

Also, the ecliptic – the sun’s yearly pathway in front of the backdrop stars – intersects the galactic equator in Sagittarius.

Sagittarius as depicted in Urania’s Mirror, a set of constellation cards published in London in 1825. Image via Wikimedia.

The constellation versus the sign

In our modern times, the sun passes in front of the constellation Sagittarius from about December 18 to January 20. These dates are off by about a month from what you read on the horoscope page. The sun moves through the sign Sagittarius from about November 21 to December 21.

Yes, there is a difference between an astronomical constellation and an astrological sign! Keep in mind that we’re talking about the constellation Sagittarius in this article. The horoscope is referring to the sign Sagittarius.

By definition, the sun enters the sign Sagittarius whenever the sun is precisely 30 degrees west of the December solstice point. Then, on the December solstice, the sun enters the sign Capricorn.

While the signs remain fixed relative to the solstices and equinoxes, the solstices and equinox points move 30 degrees westward in front of the constellations – or backdrop stars – in about 2,160 years.

The constellation boundaries were formally defined by the International Astronomical Union (IAU) in 1930. Based on the present IAU boundaries, the December solstice point moved into the constellation Sagittarius in the year 131 BCE and will move into the constellation Ophiuchus in 2269 CE.

Bottom line: Look for the constellation Sagittarius on an August or September evening. The brightest stars in Sagittarius form the distinctive shape of a teapot. And the spout of the Teapot points to the center of the Milky Way galaxy.

Teapot of Sagittarius points to the Milky Way’s center

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A first! 3 supermassive black holes discovered in 1 galaxy

This is distant galaxy J0148-4214. The black circles show the locations of 3 supermassive black holes (not to scale). This Webb image marks the first ever observation of 3 supermassive black holes in a single galaxy. Image via Hannah Übler/ MPE.

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3 supermassive black holes in a single galaxy

Scientists think most large galaxies have supermassive black holes at their hearts. And, earlier this year, astronomers from the Max Planck Institute for Radio Astronomy said they’ve detected the first pair of supermassive black holes at the center of a galaxy … two monster black holes so close they could merge. Now, on August 12, 2026, astronomers from the Max Planck Institute for Extraterrestrial Physics announced that – for the first time – they’ve detected three supermassive black holes in one galaxy.

Two of these black hole triplets lie near one another and the center of their galaxy. They are only 620 light-years apart. One of these two is the most massive of the three at 80 million solar masses (a single solar mass is a unit of measurement in astronomy). The other central black hole is the least massive with just 600,000 solar masses. The third black hole looms on the galaxy’s outskirts, about 5,500 light-years from the center, with 2 million times the mass of our sun.

The galactic home of these three black holes is called J0148-4214. It lies 12.5 billion light-years away from us, in the very early universe. So we’re seeing it as it appeared about 1.2 billion years after the Big Bang, the initiation of our universe.

The researchers published their peer-reviewed study in the journal Astronomy & Astrophysics on August 12, 2026.

Black holes in the early universe

These early-universe black holes are hungry! All three are actively accreting, or consuming nearby material in a disk. That’s unlike the supermassive black hole at the center of our own Milky Way galaxy, and other galaxies near us in space. Their older supermassive black holes appear more quiescent.

So the researchers say these early active black holes can provide insight into how our universe grew into what we see today.

Hannah Übler of the Max Planck Institute for Extraterrestrial Physics led the new triple-black-hole study. Übler said:

This is the first evidence of three active black holes in a single galaxy in the distant universe.

It suggests that processes in the early universe were efficient at bringing massive black holes together, setting the stage for the massive black hole mergers we expect to detect with future gravitational wave observatories.

Scientists have long thought that black hole mergers in the early universe are what allowed supermassive black holes to grow so big so quickly. And now, finding three supermassive black holes in one galaxy strengthens that theory.

Seeing the 3 supermassive black holes

So these three black holes have 80 million, 2 million and 6 thousand times the mass of our sun. And while you might think the most massive of the three is the greediest gobbler of nearby gas and dust, analysis suggests that the smallest of the black holes is actually accreting (gaining material) at the fastest rate. In fact, the hungry little black hole is:

… exceeding the maximum accretion rate predicted by basic theories of black hole growth (the Eddington limit).

So … another mystery!

How did the scientists spot these three black holes? They used the Webb space telescope’s NIRSpec instrument to examine the galaxy’s spectral signature. This breakdown in the wavelengths of light allowed them to see hydrogen moving at high velocities. Without this tool, the scientists would not have been able to see the black holes as separate objects. So they likely would only have identified one black hole in the galaxy.

A merger in the making

The data from Webb allowed the scientists to identify three black holes and discover their masses. Co-author Giovanni Mazzolari of MPE said:

The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates, and the stellar mass of the galaxy. We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that.

And the scientists say the central two black holes are on a collision course. They expect them to merge within the next few hundred million years. Co-author Roberto Maiolino of the University of Cambridge said:

These results are extremely exciting. They suggest that black hole merging may be an additional, fast route for their rapid growth in the early universe.

What about the third black hole? Astronomers have two scenarios. It could someday merge with the central black holes. Or it could have already been kicked out of the inner circle during a previous merger of black holes.

Bottom line: For the first time, astronomers have discovered three supermassive black holes in a single galaxy in the early universe. The two central black holes may merge in a few hundred million years.

Source: BlackTHUNDER: Evidence of three massive black holes in a z ? 5 galaxy

Via MPE

The post A first! 3 supermassive black holes discovered in 1 galaxy first appeared on EarthSky.

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This is distant galaxy J0148-4214. The black circles show the locations of 3 supermassive black holes (not to scale). This Webb image marks the first ever observation of 3 supermassive black holes in a single galaxy. Image via Hannah Übler/ MPE.

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

3 supermassive black holes in a single galaxy

Scientists think most large galaxies have supermassive black holes at their hearts. And, earlier this year, astronomers from the Max Planck Institute for Radio Astronomy said they’ve detected the first pair of supermassive black holes at the center of a galaxy … two monster black holes so close they could merge. Now, on August 12, 2026, astronomers from the Max Planck Institute for Extraterrestrial Physics announced that – for the first time – they’ve detected three supermassive black holes in one galaxy.

Two of these black hole triplets lie near one another and the center of their galaxy. They are only 620 light-years apart. One of these two is the most massive of the three at 80 million solar masses (a single solar mass is a unit of measurement in astronomy). The other central black hole is the least massive with just 600,000 solar masses. The third black hole looms on the galaxy’s outskirts, about 5,500 light-years from the center, with 2 million times the mass of our sun.

The galactic home of these three black holes is called J0148-4214. It lies 12.5 billion light-years away from us, in the very early universe. So we’re seeing it as it appeared about 1.2 billion years after the Big Bang, the initiation of our universe.

The researchers published their peer-reviewed study in the journal Astronomy & Astrophysics on August 12, 2026.

Black holes in the early universe

These early-universe black holes are hungry! All three are actively accreting, or consuming nearby material in a disk. That’s unlike the supermassive black hole at the center of our own Milky Way galaxy, and other galaxies near us in space. Their older supermassive black holes appear more quiescent.

So the researchers say these early active black holes can provide insight into how our universe grew into what we see today.

Hannah Übler of the Max Planck Institute for Extraterrestrial Physics led the new triple-black-hole study. Übler said:

This is the first evidence of three active black holes in a single galaxy in the distant universe.

It suggests that processes in the early universe were efficient at bringing massive black holes together, setting the stage for the massive black hole mergers we expect to detect with future gravitational wave observatories.

Scientists have long thought that black hole mergers in the early universe are what allowed supermassive black holes to grow so big so quickly. And now, finding three supermassive black holes in one galaxy strengthens that theory.

Seeing the 3 supermassive black holes

So these three black holes have 80 million, 2 million and 6 thousand times the mass of our sun. And while you might think the most massive of the three is the greediest gobbler of nearby gas and dust, analysis suggests that the smallest of the black holes is actually accreting (gaining material) at the fastest rate. In fact, the hungry little black hole is:

… exceeding the maximum accretion rate predicted by basic theories of black hole growth (the Eddington limit).

So … another mystery!

How did the scientists spot these three black holes? They used the Webb space telescope’s NIRSpec instrument to examine the galaxy’s spectral signature. This breakdown in the wavelengths of light allowed them to see hydrogen moving at high velocities. Without this tool, the scientists would not have been able to see the black holes as separate objects. So they likely would only have identified one black hole in the galaxy.

A merger in the making

The data from Webb allowed the scientists to identify three black holes and discover their masses. Co-author Giovanni Mazzolari of MPE said:

The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates, and the stellar mass of the galaxy. We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that.

And the scientists say the central two black holes are on a collision course. They expect them to merge within the next few hundred million years. Co-author Roberto Maiolino of the University of Cambridge said:

These results are extremely exciting. They suggest that black hole merging may be an additional, fast route for their rapid growth in the early universe.

What about the third black hole? Astronomers have two scenarios. It could someday merge with the central black holes. Or it could have already been kicked out of the inner circle during a previous merger of black holes.

Bottom line: For the first time, astronomers have discovered three supermassive black holes in a single galaxy in the early universe. The two central black holes may merge in a few hundred million years.

Source: BlackTHUNDER: Evidence of three massive black holes in a z ? 5 galaxy

Via MPE

The post A first! 3 supermassive black holes discovered in 1 galaxy first appeared on EarthSky.

from EarthSky https://ift.tt/uUWbwND

Voyager 2 confirms Neptune’s rings on August 22 in 1989

This brightened Voyager 2 image reveals the faint and continuous rings of Neptune. Voyager 2 confirmed the existence of Neptune’s rings on August 22, 1989. Image via NASA/ JPL.

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Neptune’s rings confirmed August 22, 1989

By the late 1980s, astronomers suspected that there are rings around Neptune, our solar system’s outermost major planet. After all, the next planet inward, Uranus, has rings (found in 1977). So does Jupiter (found in 1979) and Saturn (first glimpsed through early telescopes in the 1600s).

Then, watching from Earth in 1984, astronomers recorded extra blinks before and after Neptune passed in front of a distant star. That added to the evidence that Neptune had at least a partial ring system. But it was NASA’s Voyager 2 spacecraft that provided the first photographic proof of the existence of Neptune’s rings on August 22, 1989.

At the time, the spacecraft was a few days out from its closest encounter with the planet on August 25, 1989. As Neptune began looming large in Voyager’s cameras, the spacecraft photographed a faint but continuous ring system encircling the planet. The images of Neptune’s rings confirmed astronomers’ long-held suspicions.

Names for Neptunian rings

Today, Voyager 2 remains the only earthly spacecraft to have encountered Neptune. But since Voyager’s 1989 flyby, the Hubble Space Telescope, the James Webb Space Telescope, and Earth-based telescopes have imaged the two brightest rings of Neptune. Astronomers named those two Neptunian rings Adams and Le Verrier. They’re named for John Couch Adams and Urbain Jean Joseph Le Verrier, whose independent calculations helped find Neptune’s position in the sky – and thus led to its discovery – in 1846.

There are also three more rings around Neptune: Galle, Lassell, Arago. So moving outward from near the planet, the main rings are Galle, Leverrier, Lassell, Arago, and Adams.

Peculiar ring arcs

Today, we know that Neptune has at least five main rings. Plus, it has four prominent ring arcs. The arcs are peculiar clumps of dust. Astronomers struggled to understand their existence, because the laws of motion predict these arcs should spread out into a uniform ring over short timescales. Scientists now believe the gravitational effects of Galatea, a moon just inward from the ring, confine the arcs.

Also, four of the prominent arcs have names. Astronomers call them Liberté (Liberty), Egalité (Equality), Fraternité (Fraternity), and Courage. They’re located in the outermost ring, Adams.

By blocking out Neptune the backlit rings shine through. The wide-angle camera on Voyager 2 made this image from two 591-second exposures of the rings taken on August 26, 1989, from 175,000 miles (281,000 km) away. Image via NASA/ JPL.

Bottom line: NASA’s Voyager 2 spacecraft confirmed the discovery of Neptune’s rings on August 22, 1989, when it took images of a faint, continuous ring system around the planet.

Read more: Webb sees Neptune’s rings and moons

The post Voyager 2 confirms Neptune’s rings on August 22 in 1989 first appeared on EarthSky.

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This brightened Voyager 2 image reveals the faint and continuous rings of Neptune. Voyager 2 confirmed the existence of Neptune’s rings on August 22, 1989. Image via NASA/ JPL.

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

Neptune’s rings confirmed August 22, 1989

By the late 1980s, astronomers suspected that there are rings around Neptune, our solar system’s outermost major planet. After all, the next planet inward, Uranus, has rings (found in 1977). So does Jupiter (found in 1979) and Saturn (first glimpsed through early telescopes in the 1600s).

Then, watching from Earth in 1984, astronomers recorded extra blinks before and after Neptune passed in front of a distant star. That added to the evidence that Neptune had at least a partial ring system. But it was NASA’s Voyager 2 spacecraft that provided the first photographic proof of the existence of Neptune’s rings on August 22, 1989.

At the time, the spacecraft was a few days out from its closest encounter with the planet on August 25, 1989. As Neptune began looming large in Voyager’s cameras, the spacecraft photographed a faint but continuous ring system encircling the planet. The images of Neptune’s rings confirmed astronomers’ long-held suspicions.

Names for Neptunian rings

Today, Voyager 2 remains the only earthly spacecraft to have encountered Neptune. But since Voyager’s 1989 flyby, the Hubble Space Telescope, the James Webb Space Telescope, and Earth-based telescopes have imaged the two brightest rings of Neptune. Astronomers named those two Neptunian rings Adams and Le Verrier. They’re named for John Couch Adams and Urbain Jean Joseph Le Verrier, whose independent calculations helped find Neptune’s position in the sky – and thus led to its discovery – in 1846.

There are also three more rings around Neptune: Galle, Lassell, Arago. So moving outward from near the planet, the main rings are Galle, Leverrier, Lassell, Arago, and Adams.

Peculiar ring arcs

Today, we know that Neptune has at least five main rings. Plus, it has four prominent ring arcs. The arcs are peculiar clumps of dust. Astronomers struggled to understand their existence, because the laws of motion predict these arcs should spread out into a uniform ring over short timescales. Scientists now believe the gravitational effects of Galatea, a moon just inward from the ring, confine the arcs.

Also, four of the prominent arcs have names. Astronomers call them Liberté (Liberty), Egalité (Equality), Fraternité (Fraternity), and Courage. They’re located in the outermost ring, Adams.

By blocking out Neptune the backlit rings shine through. The wide-angle camera on Voyager 2 made this image from two 591-second exposures of the rings taken on August 26, 1989, from 175,000 miles (281,000 km) away. Image via NASA/ JPL.

Bottom line: NASA’s Voyager 2 spacecraft confirmed the discovery of Neptune’s rings on August 22, 1989, when it took images of a faint, continuous ring system around the planet.

Read more: Webb sees Neptune’s rings and moons

The post Voyager 2 confirms Neptune’s rings on August 22 in 1989 first appeared on EarthSky.

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Teapot of Sagittarius points to the Milky Way’s center

The Teapot asterism in the constellation Sagittarius marks the direction in our sky of the center of our Milky Way galaxy. The green line marks the ecliptic, or sun’s path across our sky. And we’ve marked the winter solstice point, where the sun resides around December 21. Chart via EarthSky.

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

Come to know the Teapot of Sagittarius

Our Milky Way galaxy is a vast collection of hundreds of billions of stars. We’re not in the galaxy’s center, but instead about 2/3 of the way out from center, in one of the Milky Way’s spiral arms. And on August evenings, under a dark sky, all of us on Earth can gaze toward the galaxy’s center.

The band of the Milky Way gets broader and brighter in the direction of the center. And in that direction, you’ll find a famous asterism called the Teapot, in the constellation Sagittarius.

The Teapot’s pattern is distinctive. It’s easy to see it as an earthly teapot. You’ll find it southward on August evenings from the Northern Hemisphere, and overhead from the Southern Hemisphere.

Even if your sky isn’t dark, once you find the Teapot, you can use it to guide your mind’s eye to the star-rich center of our galaxy. A supermassive black hole lies at the galaxy’s heart, with some 4 million times the mass of our sun. It’s called Sagittarius A* (Sagittarius A-Star).

How to spot the Teapot

You’ll want a fairly dark sky to find the Teapot. A suburban sky will likely work, if you’re not standing under a streetlight. You can see the Teapot even if you can’t see the starry band of the Milky Way.

If you’re in the Northern Hemisphere, look southward on August evenings a couple of hours after sunset. If you’re in the Southern Hemisphere, look overhead.

The Teapot and Sagittarius are best viewed during the evening hours from about July to September.

Want a more exact location for Sagittarius? Try Stellarium, which will let you set a date and time from your exact location on the globe.

The center of the galaxy is located between the Tail of Scorpius and the Teapot of Sagittarius. In a dark sky, you can see clouds of “steam” ascending from the Teapot’s spout in this region. Really, they are stars in our Milky Way galaxy. Chart via Astro Bob. Used with permission.

The Teapot looks like its name

The constellation Sagittarius is supposed to be a centaur, a mythical half man/half horse creature, carrying a bow and arrow. But good luck spotting the centaur in these stars!

On the other hand, the Teapot – unlike many star patterns – looks just like its namesake. That’s because the Teapot appears to have a handle, spout and lid, as any earthly teapot would. And just be sure to head to a dark sky for your best views of this Milky Way region.

Once you’ve found the Teapot, assuming you have a dark sky, you can see “steam” billowing out of the spout. Gaze into the midst of this “steam” – actually billions of stars – and you’ll be gazing toward the center of our Milky Way galaxy.

The Teapot is highest in the evening sky in August

Because the sun passes in front of Sagittarius from about December 18 to January 20, the Teapot isn’t visible then. However, about half a year later – on July 1 – the Teapot climbs to its highest point for the night around midnight (1 a.m. daylight saving time or DST), when it appears due south as seen from the Northern Hemisphere or due north as seen from the Southern Hemisphere. In August, the Teapot – and the Milky Way’s center – reach their highest points for the night during the evening hours.

By the way, another noteworthy point lies in the direction of the Teapot in space. It’s the point at which the sun shines on the December solstice around December 21 each year.

The center of our Milky Way

The center of our galaxy is some 26,000 light-years away. We can’t see directly into it, because this region is shrouded by dust and gas clouds. But studies by astronomers have shown that, when we look in this direction, we’re looking toward the supermassive black hole located at our galaxy’s heart. This black hole has some 4 million times our sun’s mass. It’s known as Sagittarius A*.

Now sweep the area around the Teapot with binoculars or a telescope. You’ll see many faint fuzzy objects pop into view. They’re star clusters and nebulae (gas clouds) located in the disk of our galaxy, in the direction of the galaxy’s center.

So, find the Teapot on a dark night – when the moon is out of the way – and enjoy all it has to offer.

View at EarthSky Community Photos. | Catherine Hyde in Cambria, California, captured this photo of the Milky Way on July 10, 2023. Catherine wrote: “This is the Teapot asterism rising from behind a tree. I’ve heard if you can capture the galactic center (Milky Way) behind it, it looks like steam coming out of the spout. I was surprised by how many deep-sky objects I had captured, so I annotated the image.” Thank you, Catherine!

Bottom line: As you gaze toward the famous Teapot asterism in the constellation Sagittarius, you’re looking toward the center of our Milky Way galaxy.

Read more: Milky Way’s black hole emits rapid-fire flickers and flares

The post Teapot of Sagittarius points to the Milky Way’s center first appeared on EarthSky.

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The Teapot asterism in the constellation Sagittarius marks the direction in our sky of the center of our Milky Way galaxy. The green line marks the ecliptic, or sun’s path across our sky. And we’ve marked the winter solstice point, where the sun resides around December 21. Chart via EarthSky.

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

Come to know the Teapot of Sagittarius

Our Milky Way galaxy is a vast collection of hundreds of billions of stars. We’re not in the galaxy’s center, but instead about 2/3 of the way out from center, in one of the Milky Way’s spiral arms. And on August evenings, under a dark sky, all of us on Earth can gaze toward the galaxy’s center.

The band of the Milky Way gets broader and brighter in the direction of the center. And in that direction, you’ll find a famous asterism called the Teapot, in the constellation Sagittarius.

The Teapot’s pattern is distinctive. It’s easy to see it as an earthly teapot. You’ll find it southward on August evenings from the Northern Hemisphere, and overhead from the Southern Hemisphere.

Even if your sky isn’t dark, once you find the Teapot, you can use it to guide your mind’s eye to the star-rich center of our galaxy. A supermassive black hole lies at the galaxy’s heart, with some 4 million times the mass of our sun. It’s called Sagittarius A* (Sagittarius A-Star).

How to spot the Teapot

You’ll want a fairly dark sky to find the Teapot. A suburban sky will likely work, if you’re not standing under a streetlight. You can see the Teapot even if you can’t see the starry band of the Milky Way.

If you’re in the Northern Hemisphere, look southward on August evenings a couple of hours after sunset. If you’re in the Southern Hemisphere, look overhead.

The Teapot and Sagittarius are best viewed during the evening hours from about July to September.

Want a more exact location for Sagittarius? Try Stellarium, which will let you set a date and time from your exact location on the globe.

The center of the galaxy is located between the Tail of Scorpius and the Teapot of Sagittarius. In a dark sky, you can see clouds of “steam” ascending from the Teapot’s spout in this region. Really, they are stars in our Milky Way galaxy. Chart via Astro Bob. Used with permission.

The Teapot looks like its name

The constellation Sagittarius is supposed to be a centaur, a mythical half man/half horse creature, carrying a bow and arrow. But good luck spotting the centaur in these stars!

On the other hand, the Teapot – unlike many star patterns – looks just like its namesake. That’s because the Teapot appears to have a handle, spout and lid, as any earthly teapot would. And just be sure to head to a dark sky for your best views of this Milky Way region.

Once you’ve found the Teapot, assuming you have a dark sky, you can see “steam” billowing out of the spout. Gaze into the midst of this “steam” – actually billions of stars – and you’ll be gazing toward the center of our Milky Way galaxy.

The Teapot is highest in the evening sky in August

Because the sun passes in front of Sagittarius from about December 18 to January 20, the Teapot isn’t visible then. However, about half a year later – on July 1 – the Teapot climbs to its highest point for the night around midnight (1 a.m. daylight saving time or DST), when it appears due south as seen from the Northern Hemisphere or due north as seen from the Southern Hemisphere. In August, the Teapot – and the Milky Way’s center – reach their highest points for the night during the evening hours.

By the way, another noteworthy point lies in the direction of the Teapot in space. It’s the point at which the sun shines on the December solstice around December 21 each year.

The center of our Milky Way

The center of our galaxy is some 26,000 light-years away. We can’t see directly into it, because this region is shrouded by dust and gas clouds. But studies by astronomers have shown that, when we look in this direction, we’re looking toward the supermassive black hole located at our galaxy’s heart. This black hole has some 4 million times our sun’s mass. It’s known as Sagittarius A*.

Now sweep the area around the Teapot with binoculars or a telescope. You’ll see many faint fuzzy objects pop into view. They’re star clusters and nebulae (gas clouds) located in the disk of our galaxy, in the direction of the galaxy’s center.

So, find the Teapot on a dark night – when the moon is out of the way – and enjoy all it has to offer.

View at EarthSky Community Photos. | Catherine Hyde in Cambria, California, captured this photo of the Milky Way on July 10, 2023. Catherine wrote: “This is the Teapot asterism rising from behind a tree. I’ve heard if you can capture the galactic center (Milky Way) behind it, it looks like steam coming out of the spout. I was surprised by how many deep-sky objects I had captured, so I annotated the image.” Thank you, Catherine!

Bottom line: As you gaze toward the famous Teapot asterism in the constellation Sagittarius, you’re looking toward the center of our Milky Way galaxy.

Read more: Milky Way’s black hole emits rapid-fire flickers and flares

The post Teapot of Sagittarius points to the Milky Way’s center first appeared on EarthSky.

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Voyager 2 spacecraft launched 49 years ago today

John Casani was the Voyager project manager in 1977. Here he is holding a small flag that was folded and sewn into the thermal blankets of the Voyager 2 spacecraft before launch. Voyager 2 is behind him, and the famous golden record the Voyagers carried is in front. Read about the story of the record here.

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Voyager 2 launched 49 years ago

NASA launched the phenomenal Voyager 2 space probe to the outer solar system on August 20, 1977. Voyager 2 went up some weeks before its twin craft, Voyager 1, which moved faster and eventually passed it.

Later, Voyager 1 became the first spacecraft to leave the solar system in August 2012. It is now the most distant human-made object from Earth. In fact, on November 18, 2026, Voyager 1 spacecraft will be 16,094,799,096 miles (25,902,068,356 kilometers) away from Earth. That’s the distance light travels in 24 hours, also known as one light-day.

Voyager 2 left the solar system in November 2018. So both Voyagers are now in interstellar space. Voyager 2 was left flying solo for seven months in 2020 while repairs were made to the radio antenna that commands it. The only radio antenna that can command the space probe – the Deep Space Station 43 (DSS43) antenna in Canberra, Australia – was then offline during the repairs. After the completion of the repairs, communications were restored.

Today, transmissions from Voyager 2 are faint and travel a long distance. But the craft still transmits and receives data via NASA’s Deep Space Network. Scientists believe it will be able to continue communications through 2027.

Where are Voyager 1 and 2 now?

As Voyager 2 sped away from Earth, it looked back and acquired this image of a crescent-shaped Earth and moon – the first of its kind ever taken by a spacecraft – on September 18, 1977. Voyager 2 was then 7.3 million miles (11.7 million kilometers) from Earth. Image via NASA.

Voyager 2 is the only spacecraft to visit all 4 gas giant planets

A region of Jupiter’s southern hemisphere extending from the Great Red Spot to the south pole. Before the Voyagers, we did not know Jupiter’s banded atmosphere, or Red Spot, contained so much detail. Image via NASA/ JPL/ CalTech.

Before the Voyagers, we did not know that Saturn’s rings consisted of thousands of individual ringlets. In this Voyager 2 image from 1981, you can also see the mysterious “spokes” in Saturn’s rings. Image via NASA.

Voyager 2 is still the only spacecraft to have visited the outer planets Uranus and Neptune. Here is Uranus as seen by Voyager 2 in 1986. To the spacecraft, the planet appeared as a featureless blue ball. Image via NASA.

Voyager 2 passed Neptune in 1989. It saw cloud features in Neptune’s atmosphere, which were tracked by Voyager’s cameras as the craft swept past. Image via NASA.

NASA Voyager photo gallery

The Grand Tour was a phenomenal success

Initially, NASA conceived of the Voyager mission in the 1960s as a planetary Grand Tour to study the outer planets. The fact that all four outer planets would be, temporarily, within one quadrant of the solar system around the decade of the 1980s inspired the idea. However, funding difficulties intervened, and for a time it appeared the Grand Tour would never be realized.

Ultimately, Voyager 2’s launch took advantage not only of this particular configuration of planets, but also of a new technique called a gravity assist. By using the gravity of planets for propulsion and direction, this technique let the craft visit all four outer planets (Jupiter, Saturn, Uranus and Neptune), while requiring a minimal amount of propellant and less time traveling between planets.

The plan hinged on whether Voyager 1 would be able to perform a successful flyby of Saturn’s large and intriguing moon Titan. Of course Voyager 1 succeeded, and Voyager 2 got the go-ahead to travel on toward Uranus and Neptune, ultimately realizing the vision of the planetary Grand Tour.

Voyager 2 remains the only craft from Earth to have visited Uranus and Neptune.

Bottom line: The phenomenal Voyager 2 spacecraft launched on August 20, 1977. It ultimately visited all four outer planets – Jupiter, Saturn, Uranus and Neptune – and remains the only craft from Earth to have done so.

JPL/ NASA Voyager website

Read more: Voyager 2 sends back insights on interstellar space

The post Voyager 2 spacecraft launched 49 years ago today first appeared on EarthSky.

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John Casani was the Voyager project manager in 1977. Here he is holding a small flag that was folded and sewn into the thermal blankets of the Voyager 2 spacecraft before launch. Voyager 2 is behind him, and the famous golden record the Voyagers carried is in front. Read about the story of the record here.

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

Voyager 2 launched 49 years ago

NASA launched the phenomenal Voyager 2 space probe to the outer solar system on August 20, 1977. Voyager 2 went up some weeks before its twin craft, Voyager 1, which moved faster and eventually passed it.

Later, Voyager 1 became the first spacecraft to leave the solar system in August 2012. It is now the most distant human-made object from Earth. In fact, on November 18, 2026, Voyager 1 spacecraft will be 16,094,799,096 miles (25,902,068,356 kilometers) away from Earth. That’s the distance light travels in 24 hours, also known as one light-day.

Voyager 2 left the solar system in November 2018. So both Voyagers are now in interstellar space. Voyager 2 was left flying solo for seven months in 2020 while repairs were made to the radio antenna that commands it. The only radio antenna that can command the space probe – the Deep Space Station 43 (DSS43) antenna in Canberra, Australia – was then offline during the repairs. After the completion of the repairs, communications were restored.

Today, transmissions from Voyager 2 are faint and travel a long distance. But the craft still transmits and receives data via NASA’s Deep Space Network. Scientists believe it will be able to continue communications through 2027.

Where are Voyager 1 and 2 now?

As Voyager 2 sped away from Earth, it looked back and acquired this image of a crescent-shaped Earth and moon – the first of its kind ever taken by a spacecraft – on September 18, 1977. Voyager 2 was then 7.3 million miles (11.7 million kilometers) from Earth. Image via NASA.

Voyager 2 is the only spacecraft to visit all 4 gas giant planets

A region of Jupiter’s southern hemisphere extending from the Great Red Spot to the south pole. Before the Voyagers, we did not know Jupiter’s banded atmosphere, or Red Spot, contained so much detail. Image via NASA/ JPL/ CalTech.

Before the Voyagers, we did not know that Saturn’s rings consisted of thousands of individual ringlets. In this Voyager 2 image from 1981, you can also see the mysterious “spokes” in Saturn’s rings. Image via NASA.

Voyager 2 is still the only spacecraft to have visited the outer planets Uranus and Neptune. Here is Uranus as seen by Voyager 2 in 1986. To the spacecraft, the planet appeared as a featureless blue ball. Image via NASA.

Voyager 2 passed Neptune in 1989. It saw cloud features in Neptune’s atmosphere, which were tracked by Voyager’s cameras as the craft swept past. Image via NASA.

NASA Voyager photo gallery

The Grand Tour was a phenomenal success

Initially, NASA conceived of the Voyager mission in the 1960s as a planetary Grand Tour to study the outer planets. The fact that all four outer planets would be, temporarily, within one quadrant of the solar system around the decade of the 1980s inspired the idea. However, funding difficulties intervened, and for a time it appeared the Grand Tour would never be realized.

Ultimately, Voyager 2’s launch took advantage not only of this particular configuration of planets, but also of a new technique called a gravity assist. By using the gravity of planets for propulsion and direction, this technique let the craft visit all four outer planets (Jupiter, Saturn, Uranus and Neptune), while requiring a minimal amount of propellant and less time traveling between planets.

The plan hinged on whether Voyager 1 would be able to perform a successful flyby of Saturn’s large and intriguing moon Titan. Of course Voyager 1 succeeded, and Voyager 2 got the go-ahead to travel on toward Uranus and Neptune, ultimately realizing the vision of the planetary Grand Tour.

Voyager 2 remains the only craft from Earth to have visited Uranus and Neptune.

Bottom line: The phenomenal Voyager 2 spacecraft launched on August 20, 1977. It ultimately visited all four outer planets – Jupiter, Saturn, Uranus and Neptune – and remains the only craft from Earth to have done so.

JPL/ NASA Voyager website

Read more: Voyager 2 sends back insights on interstellar space

The post Voyager 2 spacecraft launched 49 years ago today first appeared on EarthSky.

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