Fornax the Furnace lies high in the Southern Hemisphere sky on December evenings. In fact, it’s tucked in a bend of the constellation Eridanus the River. None of the stars in Fornax is particularly bright, but the constellation does hold some wonderful gems in its darker depths: at least six star systems with exoplanets, the Fornax Dwarf galaxy (a satellite galaxy of the Milky Way), the Fornax Cluster of galaxies, a cosmic filament showing the largest rotation in the universe and the amazing Hubble Ultra Deep Field image. By the way, Fornax is one of 14 constellations that Nicolas Louis de Lacaille named in the mid-1700s.

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Fornax the Furnace and its stars

Deep in the Southern Hemisphere, Fornax the Furnace is a devilish constellation to find because of its dim stars. Its brightest star, Alpha Fornacis, has a magnitude of only 3.9. This star lies about 46 light-years from Earth. The second brightest star, Beta Fornacis, with a magnitude of 4.4, lies 169 light-years away. Sometimes people point to a third star of Fornax in order to trace out a flattened triangle in this region of space. The third brightest star is Nu Fornacis with magnitude 4.6, 357 light-years away.

So far, scientists have found six star systems in Fornax to be harboring planets. One of the stars, HR 858 at magnitude 6.3, is just barely visible to the unaided eye for those with good eyesight. The Transiting Exoplanet Survey Satellite TESS found at least three exoplanets orbiting this star in 2019.

Fornax Dwarf, the satellite galaxy

One of the satellite galaxies of the Milky Way lies in the direction of Fornax the Furnace. The Fornax Dwarf is an elliptical collection of stars with six notable globular clusters. One of its globular clusters, NGC 1049, was discovered by John Herschel on October 19, 1835. But the galaxy itself wasn’t discovered until more than 100 years later, by Harlow Shapley in 1938.

Galaxies clusters in Fornax the Furnace

Also, one of the closest galaxy clusters to our Milky Way is the Fornax Cluster. It lies 62 million light-years away in the direction of Fornax and spills over into Eridanus the River. The brightest galaxy in the cluster, NGC 1316, shines at magnitude 8.5, meaning that you can pick it up with binoculars from under dark skies. NGC 1316, which also goes by the name Fornax A, is the fourth brightest radio source in the sky.

Hubble Ultra Deep Field

Since this is an “empty” region of sky, giving us a view into the wider universe with few obstructions, the Hubble Space Telescope aimed in the direction of Fornax to take an image of the early universe in 2003. The Hubble Ultra Deep Field shows a small piece of the universe packed with galaxies, looking back in space and time as far as 13 billion years ago.

Largest rotation in the universe

The galaxies in our universe are strung together in long filaments and webs, creating the grand structure of the cosmos. Scientists have detected that one enormous filament of galaxies is rotating. These corkscrewing galaxies, located in the direction of Fornax, display the largest rotation in the universe.

Bottom line: Fornax the Furnace is a constellation in the Southern Hemisphere that appears as a few dim stars to the unaided eye but is harboring galaxies, from one orbiting the Milky Way to some at the edge of the universe.

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The constellation Sculptor is a quiet patch of dark sky that brushes the southern horizon in November for Northern Hemisphere viewers. It is one of the 14 constellations named by the French astronomer Nicolas Lacaille (1713-1762). Lacaille’s original name for this grouping of southern stars was the Sculptor’s Workshop. But these dim stars resemble neither sculptor nor workshop. You might instead pick out a triangle of stars in Sculptor, shown in the chart at the top of this post. And in addition, this small constellation has a claim to fame. It’s home to the point in the sky astronomers recognize as the South Galactic Pole.

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What is the South Galactic Pole?

Imagine us on a galactic scale within the disk of our home Milky Way galaxy. The galaxy lies all around us in space. Indeed, it spins, just as Earth spins (and as all objects in space are spinning) around a central axis. The spin axis of the Milky Way runs through its center, making our great spiral galaxy resemble a turning pinwheel. So – in much the same way we on Earth look in our sky toward Polaris, our present-day North Star – so we on Earth can look in the sky toward the north and south poles of our Milky Way galaxy.

The North Galactic Pole lies in the northern constellation Coma Berenices. Likewise, the South Galactic Pole lies in the southern constellation Sculptor. The galactic latitude of that pole would be -90 degrees.

From our earthly vantage point, we can’t see into our galaxy’s center. That’s because nearly all the Milky Way’s visible contents – gas, dust, stars – lie in the flat plane of the galaxy, at zero degrees galactic longitude. To be sure, when we look toward the Milky Way’s center, there’s a lot of stuff obscuring our view between us and the center. But looking toward the poles of the galaxy is different, however. Then we’re looking up and away from the star-rich plane of the galaxy. IN this case, we’re looking more clearly into the space beyond our galaxy. And so astronomers say that looking toward Sculptor is like looking out our galaxy’s south window.

How to find Sculptor

People in the Southern Hemisphere can spy Sculptor overhead on November evenings. For Northern Hemisphere observers, you’ll have to have a clear horizon to the south and a dark-sky site. Notably, there is one bright star is in this region of sky, and it doesn’t belong to Sculptor. Fomalhaut, with the nickname of the loneliest star, is part of the constellation Piscis Austrinus the Southern Fish. Look east of Piscis Austrinus and below Cetus the Whale with its star Diphda. See that dark empty space? That’s Sculptor.

On the other hand, the constellation’s brightest star, Alpha Sculptoris, shines at a mere magnitude 4.3. This means that if you live in a city or nearby suburb, you can’t see any of Sculptor’s stars at all. Alpha Sculptoris lies about 780 light-years from Earth.

In addition, one other notable star in this constellation is Zeta Sculptoris, at magnitude 5.0. A smattering of dimmer stars surround Zeta, giving the cluster the name the Zeta Sculptoris Cluster. Yet Zeta is not actually part of the cluster. In fact, the cluster stars are much farther away.

Deep-sky objects in the constellation Sculptor

Also, a little less than five degrees from Alpha Sculptoris is the most notable deep-sky object in this constellation: the Sculptor Galaxy. At magnitude eight, you can spot the galaxy – also known as NGC 253 – through a small telescope. The galaxy is about 13 million light-years distant, making it a member of one of the nearest groups of galaxies to Earth. The galaxy is a spiral that shows a central bar in infrared images.

Also above Alpha Sculptoris, but below the galaxy, is the South Galactic Pole. If you want to gaze toward this point in the sky with your binoculars or telescope – look out our galaxy’s “south window,” as it were – its geocentric coordinates (right ascension and declination) are RA = 0h 51m 26.00s, Dec = -27d 7m 42.0s.

Deep field images of Pandora’s Cluster

Of course, one advantage of an area of sky that is sparsely populated with stars or other bright space objects is that it makes a great target for deep field photos from the Hubble and Webb telescopes. So they focused in on Sculptor to capture the massive galaxy cluster Abell 2744, also called Pandora’s Cluster. Indeed, even more distant galaxies appear through gravitational lensing in these photos.

Bottom line: The constellation Sculptor appears best on November evenings from the Northern Hemisphere, when it lies along the southern horizon.

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Tucana the Toucan, deep in southern skies

The constellation Tucana the Toucan is visible year-round from Earth’s Southern Hemisphere. That’s because it’s near the south celestial pole, the point in the sky around which all southern stars revolve. So those of us in the Northern Hemisphere would have to travel southward on Earth’s globe to see Tucana. And, once we got there, we’d find that the stars of this constellation aren’t particularly bright or remarkable. Yet many of us know Tucana by name. Why?

It’s because this constellation is famous for being home to the Small Magellanic Cloud, the fuzzy patch in the sky that represents one of two relatively large dwarf galaxies orbiting our Milky Way. Plus, southern stargazers know that a large globular star cluster – 47 Tucanae, visible to the unaided eye – is also located within the boundaries of Tucana. In fact, this constellation’s stars are harder to pick out than the globular cluster and galaxy that anchor its southern edge.

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Stars of Tucana

The brightest star in Tucana is Alpha Tucanae, a magnitude 2.87 star that lies almost 200 light-years from Earth.

On the opposite side of the constellation from Alpha is Beta Tucanae, a star system containing six stars loosely bound together. Beta 1 is the brightest and shines at magnitude 4.36. Beta 2 shines at magnitude 4.53, and Beta 3 shines at 5.07. The whole Beta Tucanae system is an average of 140 light-years from Earth.

Small Magellanic Cloud

Despite its great distance of 197,000 light-years, the Small Magellanic Cloud is one of the closest galaxies to Earth. You can see it without optical aid as a misty, cloudy patch from dark-sky locations. The Small Magellanic Cloud is an irregular galaxy but has a central bar as part of its structure, making it look like a disturbed former spiral. It’s the smaller of the two satellite galaxies in the Southern Hemisphere skies, with the larger being the aptly named the Large Magellanic Cloud.

The Small Magellanic Cloud has many clusters and nebulae within its expanse. An excellent target for a telescope, clusters stream through its length and out one tail. The Small Magellanic Cloud’s nearby kin, the Large Magellanic Cloud, lies in the constellations Mensa and Dorado. Both of these nearby galaxies are being sucked inward by our Milky Way Galaxy and will eventually be absorbed by it.

47 Tucanae

The globular cluster 47 Tucanae also bears the catalog name NGC 104. It shines bright at magnitude 4.0 and is easily visible with the unaided eye. In excellent seeing conditions, it appears as large as the full moon. It’s the second brightest globular cluster of the Milky Way and contains millions of stars. Use binoculars or a telescope to resolve thousands of stars in the cluster.

47 Tucanae lies 14,500 light-years away. 47 Tucanae and the Small Magellanic Cloud may look close together, but that is only a line-of-sight coincidence. The Small Magellanic Cloud is about 14 times farther away.

Bonus globular cluster

Want a bonus observing target? On the opposite edge of the Small Magellanic Cloud’s curving shape from 47 Tucanae is NGC 362, another bright globular cluster. NGC 362 is a bit dimmer than 47 Tucanae, at magnitude 6.4, but still a good target in binoculars or small telescopes.

The Hubble Deep Field South

The Hubble Space Telescope took a series of famous images called “deep fields” starting in the 1990s. In these images, the space telescope stared at what mostly looks like a blank area of sky for a long period of time, allowing the faint background objects to come to light. One of these images, the Hubble Deep Field South, came from a region of Tucana.

Bottom line: Tucana the Toucan is a constellation in the Southern Hemisphere that’s a cinch to spot. Just look for our little satellite galaxy, the Small Magellanic Cloud. Two easy-to-observe globular clusters also reside here.

The post Tucana the Toucan is home to the Small Magellanic Cloud first appeared on EarthSky.

Pegasus the Flying Horse

Pegasus the Flying Horse rises in the east on autumn evenings in the Northern Hemisphere (spring evenings in the Southern Hemisphere). It dominates the sky with its giant square asterism, fittingly called the Great Square. In mythology, Pegasus figured into the greatest – surely the most elaborate – of all sky myths. This one is from ancient Greece some 3,000 years ago. According to the myth, Pegasus was the flying horse ridden by Perseus the Hero, as he swooped in to save Princess Andromeda from a sea monster. There’s more to the story, which you’ll find in the video at the top of this page.

Today, we see Pegasus as the 7th-largest of the 88 official constellations. And Pegasus is easy to find. On fall evenings in the Northern Hemisphere, this constellation climbs above the eastern horizon, reaching a spot nearly overhead by late fall.

Its asterism – the Great Square of Pegasus – is huge. The square alone is 20 degrees wide from top to bottom. That’s the span of two fist-widths held at arm’s length.

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Stars of Pegasus

As it rises in the evening, the star in the Great Square closest to the horizon is Algenib, with a magnitude of 2.8. It lies 333 light-years away. The star on the opposite corner of the square from Algenib is Scheat, a magnitude 2.4 star lying 199 light-years away. The star to the south in the square is Markab, a magnitude 2.5 star at a distance of 140 light-years. And the final star in the square is Alpheratz. Technically, Alpheratz lies just across the border of Pegasus and is actually a member of the constellation Andromeda. Alpheratz is the brightest of the four stars at magnitude 2.1 and lies 97 light-years away.

The Great Square marks the body of the flying horse. Trails leading off the west side of the square mark the front legs and head of Pegasus. Extending out from Markab, two stars at magnitude 3.4 and 3.5, Homam and Biham, lead the way to the head star, magnitude 2.4 Enif. This star will be helpful in finding the globular cluster M15.

Find the forelegs of Pegasus off of Scheat. Five degrees west of Scheat is magnitude 3.0 Matar. As the brightest leg star in Pegasus, it’s helpful in finding a couple of notable galaxies.

The asterism of the Great Square

The Great Square of Pegasus can look like a huge diamond. Think of it as a giant baseball diamond rising during playoffs month in the east after dark. Asterisms, such as the Great Square, are groups of stars that aren’t labeled as constellations but are easy to recognize.

Using Pegasus to find the Andromeda Galaxy

Pegasus is close to the constellation Andromeda, so it’s useful for star-hopping to the Andromeda galaxy. You’ll need a dark-sky site to track down Andromeda without optical aid. It’s much easier to spot with binoculars or a telescope. Follow this link for more information on how to use Pegasus to find Andromeda.

Stephan’s Quintet

Pegasus is home to many galaxy clusters. The most famous is probably Stephan’s Quintet, a favorite target among astrophotographers. This tight gathering of five galaxies has a magnitude of 13.6. The largest and brightest, NGC 7320, has a small redshift compared to the other four, revealing that it is probably not a physical member of the group and just a line-of-sight coincidence.

Fun fact: In the 1946 movie It’s a Wonderful Life, angels in heaven discussing George Bailey are depicted as the galaxies in Stephan’s Quintet.

Other galaxies in Pegasus the Flying Horse

Three other notable galaxy clusters lie in Pegasus. The brightest is magnitude 9.5 and is just half a degree from Stephan’s Quintet. The cluster has the curious name Deer Lick Group. Follow Scheat to Matar and then about 4.5 degrees farther and slightly north of the direction you were heading. This will bring you to the Deer Lick Group, NGC 7331. Here you’ll find one large spiral galaxy and a spattering of smaller ones.

The Pegasus I Cluster lies on the southern edge of the constellation not far from the circlet of Pisces. At a distance of 8 degrees from Markab on the sky’s dome, the Pegasus I Cluster is a magnitude 11.1 grouping. The galaxy cluster requires a large telescope to see or a long-exposure photograph, but it reveals a beautiful and striking number of galaxies.

The Pegasus II Cluster lies back within the square of Pegasus. Halfway between Alpheratz and Scheat, it lies just inside the border of a line that would be drawn connecting these two stars. A bit dimmer at magnitude 12.6, the Pegasus II Cluster (NGC 7720) is a powerful radio source, the target of much scientific study.

Globular Cluster M15 in Pegasus the Flying Horse

One other deep-sky object of note in Pegasus is the globular cluster M15. You can find M15 easily using the head and neck stars of Pegasus. Start with the star Markab and go to the two dimmer stars that mark the neck. From the last star of the neck (Biham) to the brighter head star Enif, continue a line straight out for a little more than 4 degrees. Here you will find the magnitude 6.4 globular cluster M15. It lies about 33,600 light-years away and will show up nicely in a pair of binoculars.

First exoplanet around a sun-like star

Astronomers discovered the first exoplanet orbiting a sun-like star in the constellation Pegasus. They named the planet 51 Pegasi b after the star it orbits. Didier Queloz and Michel Mayor discovered the planet in 1995 and received the Nobel Prize in Physics for their discovery in 2019.

Bottom line: Pegasus the Flying Horse is a giant constellation that dominates autumn skies in the Northern Hemisphere (spring skies in the Southern Hemisphere). The constellation contains a famous asterism called the Great Square.

The post Pegasus the Flying Horse, and the best sky story ever first appeared on EarthSky.

The constellation Andromeda is named for the daughter of Queen Cassiopeia and King Cepheus of Greek mythology. Andromeda has the nickname of the Chained Lady because her parents chained her up and offered her as a sacrifice to appease the sea monster Cetus. In the story, she is saved by Perseus and eventually becomes his queen. All these mythological characters are now visible as constellations in the night sky.

How to find the constellation Andromeda

Andromeda is easy to find because of the company it keeps. The W-shaped constellation of Cassiopeia points toward Andromeda. Andromeda is also next to the Great Square of Pegasus. In fact, one of the stars of the Great Square actually belongs to Andromeda.

November is an excellent month to try to spot Andromeda the Chained Lady. Look east after it gets dark to find the constellation already high above the horizon. Andromeda favors viewers in the Northern Hemisphere; it is not visible to those south of 40 degrees south latitude. The constellation is the 19th largest, in size, of the 88 constellations. The finder charts above can guide you to it.

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Stars of the constellation Andromeda

The brightest star in the Great Square of Pegasus actually belongs to Andromeda: the magnitude 2.06 star Alpheratz. Alpheratz lies 97 light-years away. Another magnitude 2.06 star, Mirach, lies to the upper left of Alpheratz. Mirach lies 197 light-years away and is the closest bright star to the Andromeda Galaxy. The third brightest star in Andromeda is magnitude 2.26 Almach, to the upper left of Mirach. Almach lies 355 light-years away.

Finding the Andromeda Galaxy with Cassiopeia

Although M31, the Andromeda Galaxy, is centrally located in the constellation Andromeda, it is actually easier to find by using the stars of Cassiopeia. The magnitude 3.5 galaxy can be seen as a hazy patch in a dark sky, but most people will need binoculars or a telescope to find the wide misty patch.

Andromeda stretches about three degrees across and one degree wide. It lies at a distance of approximately 2.5 million light-years from Earth, which means that as we view the light from Andromeda, we are seeing it as it was 2.5 million years ago.

To find the Andromeda Galaxy, look for the W shape of Cassiopeia. With the two V shapes that make up the W, use the V shape on the right. Imagine the V as an arrow, pointing into the constellation Andromeda. From the tip of the arrow star to the spiral galaxy, the angular distance is a little over 15 degrees. (Hold your hand at arm’s length and use your index finger and pinky spread apart to measure 15 degrees on the sky’s dome.) The arrow of Cassiopeia does not point precisely to Andromeda: You will have to look a bit to the right to find the galaxy M31.

Finding Andromeda Galaxy with Andromeda

To use a star from Andromeda to find the galaxy, start with the star that is connected to the Great Square of Pegasus. Then look left and find three stars leading away from it: a 3rd magnitude star (Delta Andromedae), Mirach and Almach. Focus on Mirach, and then look above Mirach. There are two stars in a line above it, the top one dimmer than the bottom. If you can see the highest star without optical aid, look just to its right for a slightly lighter patch of sky. Put your binoculars or a telescope on it to confirm that you’ve found Andromeda.

Observing M31, the Andromeda Galaxy

M31, at magnitude 3.5, should be easy to see once you have it located in your binoculars or telescope. The grayish patch should show an oval shape, characteristic of spiral galaxies. Two other Messier objects are within your field of view when you are looking at Andromeda. M32 and M110 and elliptical galaxies that are companions to the large Andromeda Galaxy. They also lie 2.5 million light-years away. M32 is magnitude 8.1 and is closest to the galaxy, appearing to lie on the larger spiral’s edge. M110 is magnitude 8.5 and is a bit farther away from the large spiral.

Bottom line: The constellation Andromeda the Chained Lady is most famous for containing the closest large spiral galaxy to the Milky Way.

The post The constellation Andromeda the Chained Lady first appeared on EarthSky.

Cassiopeia overhead on autumn evenings

The constellation Cassiopeia the Queen can be found high in the sky on October and November evenings, not far from Polaris, the North Star. At any time of year, you can use the Big Dipper to find Cassiopeia. These two star formations are like riders on opposite sides of a Ferris wheel. They’re part of a great spinning wheel of stars seen moving counterclockwise around Polaris, the North Star, once each day. As Cassiopeia rises upward, the Big Dipper plunges downward, and vice versa.

Some of you know how to star-hop to Polaris, the North Star, by using the Big Dipper’s pointer stars, as displayed on the sky chart below. Because the Big Dipper’s handle and Cassiopeia shine on opposite sides of Polaris, an imaginary line from any star on the Big Dipper handle through Polaris reliably points to Cassiopeia.

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Cassiopeia is bright and easy to pick out in the sky

However, you won’t need the Big Dipper and Polaris to find Cassiopeia. That’s because Cassiopeia is very easy to pick out. It’s small and compact and looks like the letter M or W, depending on the time of night and time of year.

Like the Big Dipper, Cassiopeia can be seen even on moonlit nights.

Bonus for you if you live north of about 40 degrees north latitude, about the latitude of New York City! From that latitude and farther north, the Big Dipper and Cassiopeia are both circumpolar. That means they’re always above the horizon at any time of night, all year round.

Star lore of Cassiopeia

Cassiopeia used to be known among astronomers and skywatchers alike as Cassiopeia’s Chair. In the 1930s, the International Astronomical Union gave this constellation the official name of Cassiopeia the Queen.

Cassiopeia was a queen in ancient Greek mythology. According to legend, she boasted she was more beautiful than the sea nymphs called the Nereids. Her boast angered Poseidon, god of the sea, who sent a sea monster, Cetus, to ravage the kingdom. To pacify the monster, Cassiopeia’s daughter, Princess Andromeda, was left tied to a rock by the sea. Cetus was about to devour her when Perseus the Hero looked down upon her from Pegasus, the Flying Horse. Perseus rescued the Princess, and all lived happily.

The gods were so pleased, that all of these characters were elevated to the heavens as stars. Only Cassiopeia suffered an indignity; her vanity caused her to be bound to a chair and placed in the heavens so that, as she revolves around the north celestial pole, she is sometimes in an upside-down position.

Bottom line: Spot the constellation Cassiopeia the Queen somewhere in the northern sky during much of the year, and throughout much of the night.

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How to see Delphinus

Delphinus the Dolphin is the 69th-smallest of the 88 constellations. It comes into view each year on northern summer evenings. And by northern fall, it’s well placed for viewing, arcing high across the sky each night. However, its stars are faint. So to see it, you’ll want a dark sky.

Delphinus lies just outside of the line connecting the stars Deneb in Cygnus the Swan and Altair in Aquila the Eagle. These bright stars form two corners of the famous asterism called the Summer Triangle. Scan along that line with your eye or binoculars. If your sky is dark enough, Delphinus will pop into view.

As a matter of fact, Delphinus looks very much like the animal it’s supposed to represent. Also, its faint stars form a kite shape with a tail. Then the little dolphin appears to leap out of the dark waters of the night sky.

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The stars of the Dolphin

The brightest star in the Dolphin is Beta Delphini, which shines at magnitude 3.6. The star also goes by the name Rotanev. Lying 97 light-years from Earth, it marks the point in the constellation where the Dolphin’s body connects with its tail.

The second brightest star is Alpha Delphini, at magnitude 3.7. This star nickname is Sualocin. Lying 240 light-years away, it marks the back of the Dolphin.

These two stars’ common names, Rotanev and Sualocin, are part of a puzzle. Italian astronomer Nicolaus Venator named these two stars. Can you solve the puzzle? Hint: try reading the stars’ names backward.

The nose of Delphinus is Gamma Delphini, a double star. The pair of stars shine at magnitude 4.2 and 5.1. They lie approximately 102 light-years away. The belly of the dolphin is Delta Delphini, a magnitude-4.4 star lying 203 light-years away.

Although Delphinus is a small constellation, it contains an asterism: Job’s Coffin. The four stars that mark the body of the Dolphin are the same stars that form Job’s Coffin.

The tail of the dolphin contains one star, Epsilon Delphini or Aldulfin. The magnitude-4.0 star lies 359 light-years away.

In 2013, a bright nova exploded in Delphinus not far from Sualocin. The nova, V339 Delphini, was temporarily visible to the unaided eye.

Deep-sky objects

Most of the deep-sky objects in Delphinus are quite dim. The brightest of these is a globular cluster, NGC 6934, found about 4 degrees out from the tail. NGC 6934 shines at magnitude 8.9. Another globular cluster, NGC 7006, lies off the nose of the Dolphin. If you draw a line from Sualocin through the nose star Gamma and extend it for about twice that distance, you’ll reach NGC 7006. NGC 7006 shines at magnitude 10.6.

Two planetary nebulae lie within the northwestern boundary of the constellation. Both are 12th magnitude. NGC 6905 – the Blue Flash Nebula – lies directly above the Dolphin’s back. The other planetary nebula – NGC 6891 – is above Delphinus’ tail. A number of galaxies are scattered about Delphinus; however, most of them are 12th magnitude and dimmer, making them very hard to spot without a large telescope.

News from Delphinus the Dolphin

In 2021, scientists announced they’d pinpointed the origin of a neutrino, or high-energy particle. And it came from the direction of Delphinus the Dolphin. They believe that, in a cataclysmic event, a supermassive black hole and a star drew too close together. The black hole shredded the star, which released the cosmic ray neutrino. Scientists detected the neutrino using the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station in Antarctica. So much info from such a tiny particle! Read more about the discovery.

Delphinus in history and mythology

The name Delphinus means dolphin in Latin. But it was a Greek astronomer – Ptolemy of Alexandria in the second century CE – who first cataloged these stars. In Greek mythology, Delphinus represents the dolphin sent by the sea god Poseidon to fetch Amphitrite, a goddess of the sea and one of the fabled Nereids. It’s said Poseidon chose Amphitrite from among her sisters as they performed a dance on the isle of Naxos. The dolphin carried Amphitrite to Poseidon, and she became his wife. He rewarded the dolphin by making it a constellation.

In another story, Delphinus saves the Greek poet Arion when he is attacked by robbers on a ship. They were about to kill Arion, but he begged permission to sing a final song. His captors agreed, and the poet stood on the deck of the ship and sang a dirge accompanied by his lyre. He then threw himself overboard. A dolphin who’d heard his song and been charmed by the music saved him.

Bottom line: Delphinus the Dolphin is a petite constellation that looks like the animal it’s supposed to represent. Look for the dolphin leaping under the Summer Triangle.

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Auriga has a flashy star and 3 star clusters

Auriga the Charioteer is a popular constellation for Northern Hemisphere observers in autumn, because its flashing star advertises its presence. Capella, the brightest star in Auriga, flashes red, blue and green when it’s close to the horizon and seen through a thick layer of Earth’s atmosphere. Close to Capella are a pair of stars known as The Kids, baby goats that the Charioteer carries. Auriga houses three star clusters, easy targets to hunt down with binoculars.

Auriga is a far-northern constellation. It’s close enough to the North Star that people in the northern U.S. and Canada – and similar latitudes – see it as circumpolar. In other words, they can see all or part of the constellation on any night of the year.

But some times of the year are definitely better than others. If you want to see the entirety of Auriga, start looking for the constellation and flickering Capella in Northern Hemisphere autumn. Soon you’ll be familiar with its gems and ready to go deeper by the time it moves higher and into better viewing position by winter.

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Auriga the Charioteer’s brightest star, Capella

Auriga’s brightest star, Alpha Aurigae, is a twinkling beauty named Capella. It’s a golden star, somewhat similar to our sun. In fact, if you could get some distance away from our solar system – light-years away – you might see our sun much as we see Capella. Capella is located at one corner of the constellation Auriga, marking the Charioteer’s left shoulder. By the way, Capella has the nickname the Goat Star.

Capella garners a lot of attention on autumn evenings in the Northern Hemisphere because we see it near the horizon through a thick layer of Earth’s atmosphere. The wavering atmosphere causes the light from the star to jump around, flashing bright colors of red, green and blue, making it look like an emergency vehicle parked in space. On winter evenings, Capella moves overhead near zenith and its flashiness is dampened as we look at it through a thinner layer of atmosphere.

Capella shines at a magnitude of 0.08 and is the sixth brightest star in the sky. It’s so bright because it’s nearby. Capella lies just 43 light-years away. This star marks one of the corners of the Winter Circle.

In fact, Capella is actually a pair of binary stars, both of which are yellow giant stars with small red dwarf companions.

Capella is also the closest first magnitude star to Polaris, the star currently marking our north celestial pole.

The asterism of The Kids

If you’re unsure whether you’ve identified Capella, you can always look nearby for a small triangle of stars. This triangle is an asterism, or a smaller named configuration of stars. While Capella is the Goat Star, this little triangle asterism represents The Kids. Learn more about Auriga and The Kids.

Other stars in Auriga the Charioteer

Menkalinan, the second brightest star in Auriga, marks the Charioteer’s right shoulder. This star is also fairly nearby, at a distance of 85 light-years.

Notice the star Elnath at the southern tip of Auriga. This star used to belong both to Auriga, where it was known as the heel of the Charioteer, and to the constellation Taurus, where it represented the tip of the Bull’s northern horn. In the last century, though, the International Astronomical Union decreed that this star shall belong only to Taurus!

Star clusters in Auriga the Charioteer

In a dark sky, using binoculars, you can spot some easy-to-see star clusters within Auriga: M36, M37 and M38. These Messier objects fall nearly in a line with M36 in the middle. The open star clusters have distinct personalities when viewed with magnification.

M36 bears the nickname the Pinwheel Cluster and looks reminiscent of the Pleiades. M37 is the brightest and largest of the three clusters and lies opposite the Milky Way’s galactic center, still in the plane of our galaxy but looking out to its fringes. Lastly, M38 has the nickname the Starfish Cluster. Others think this cluster looks like an X or the Greek letter Pi. What do you see?

Bottom line: From the Northern Hemisphere, look for the beautiful star Capella and its constellation Auriga the Charioteer.

The post Auriga the Charioteer and bright Capella on October evenings first appeared on EarthSky.

If you know how to locate the easy-to-spot constellation Cassiopeia the Queen, with its distinctive M or W shape, then you’re ready to find Perseus. Perseus the Hero follows Cassiopeia across the sky as seen from the Northern Hemisphere on autumn and winter evenings. Cassiopeia and Perseus are tokens of autumn in the Northern Hemisphere.

Cassiopeia’s bright stars and easy-to-recognize shape makes it easy to identify and, therefore, one of the most famous constellations in the sky. Perseus’s stars are fainter than Cassiopeia’s, and its shape is less pronounced. Because it appears at its best during the evening on cold months, I think of its brightest stars as forming an icicle dangling down from Cassiopeia, with the star Algol off to the side. If you have access to a dark sky, it will be that much easier to spot Perseus.

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Where to find Cassiopeia and Perseus

You’ll see both Cassiopeia and Perseus in the northeast on October evenings. The pair will be higher up in the evening sky in late autumn and winter. Or, as night passes, you’ll see them both ascending in the northeast, then arcing high in the north, then descending in the northwest, with Perseus following Cassiopeia all the while. Both Perseus and Cassiopeia are circumpolar from about 40 degrees north latitude to farther north. In other words, as seen from northern parts of the U.S. and Canada, they never set below the horizon, but instead circle endlessly around Polaris, the North Star.

The brightest star in Cassiopeia is Schedar. However, all the stars shine similarly bright, which is part of what makes the constellation so easy to pick out.

The brightest star in Perseus is Mirfak. But its second brightest star, Algol, gets more attention. Algol is the Demon Star. It marks the head of the demon, Medusa, while it’s also a variable star. That means it varies in brightness at a regular rate, every few days, that observers can watch without the need for optical aid.

The radiant for the Perseids

Although these constellations are best seen in the evening in autumn and winter, you can also see Cassiopeia and Perseus in the latter part of Northern Hemisphere summer, from late night until dawn. Plus, the annual Perseid meteor shower peaks around August 12 or 13, and if you trace the paths of these Perseid meteors backward, they’ll appear to originate between the two constellations.

The Double Cluster in Perseus

Last, but not least, after you’ve found Cassiopeia and Perseus, be sure to scan between them with your binoculars. Assuming your sky is dark, you’ll easily spot the magnificent Double Cluster in Perseus. This pair of open clusters makes for an easy target through a telescope and will wow your friends.

Bottom line: Cassiopeia and Perseus are neighbors in the fall sky. Use Cassiopeia’s distinctive W or M shape to locate the dimmer Perseus on autumn and winter evenings.

The post Cassiopeia and Perseus on October evenings first appeared on EarthSky.

Cassiopeia the Queen in autumn

Any late summer evening and throughout northern autumn, Cassiopeia the Queen can be found ascending in the northeast after nightfall. The shape of this constellation makes Cassiopeia’s stars very noticeable. Cassiopeia looks like the letter W (or M).

Look for the Queen starting at nightfall every September. She’ll be higher up in the northeast as autumn unfolds.

For those in the northern U.S. and Canada, Cassiopeia is circumpolar, meaning above the horizon all night long.

How to see Cassiopeia

Cassiopeia represents an ancient queen of Ethiopia. You still sometimes hear the old name for this constellation: Cassiopeia’s Chair. And some old star maps depict the queen sitting on the chair, marked by five stars.

These stars – the brightest ones in Cassiopeia – are Schedar, Caph, Gamma Cassiopeiae, Ruchbah and Segin.

Around the middle of the night during the autumn months, Cassiopeia swings above Polaris, the North Star.

Before dawn, look in the northwest.

Opposite the Big Dipper

Cassiopeia is opposite the Big Dipper in the northern sky.

That is, the two constellations lie on opposite sides of the pole star, Polaris.

So when Cassiopeia is high in the sky, as it is on evenings from about September through February, the Big Dipper is low in the sky. Every March, when the Dipper is ascending in the northeast, getting ready to appear prominent again in the evening sky, Cassiopeia can be seen descending in the northwest.

A guide to deep-sky beauties

If you have a dark sky, look below Cassiopeia in the northeast on these autumn evenings for the Double Cluster in Perseus.

These are two open star clusters, each of which consists of young stars still moving together from the primordial cloud of gas and dust that gave birth to the cluster’s stars.

These clusters are familiarly known to stargazers as H and Chi Persei.

Stargazers smile when they peer at them through their binoculars, not only because they are beautiful, but also because of their names. They are named from two different alphabets, the Greek and the Roman. Stars have Greek letter names, but most star clusters don’t. Johann Bayer (1572-1625) gave Chi Persei its Greek letter name.

Then, it’s said, he ran out of Greek letters. That’s when he used a Roman letter – the letter H – to name the other cluster.

Lore of Cassiopeia

In skylore and in Greek mythology, Cassiopeia was a beautiful and vain queen of Ethiopia. It’s said that she committed the sin of pride by boasting that both she and her daughter Andromeda were more beautiful than Nereids, or sea nymphs. Pridefulness, in mythology, is never wise.

Her boast angered Poseidon, god of the sea, who sent a sea monster (Cetus the Whale) to ravage the kingdom. To pacify the monster, Cassiopeia’s daughter, Princess Andromeda, was left tied to a rock by the sea. Cetus was about to devour her when Perseus the Hero happened by on Pegasus, the Flying Horse.

Perseus rescued the princess, and all lived happily … and the gods were pleased, so all of these characters were elevated to the heavens as stars.

But – because of her vanity – Cassiopeia suffered an indignity. At some times of the night or year, this constellation has more the shape of the letter M, and you might imagine the Queen reclining on her starry throne. At other times of year or night – as in the wee hours between midnight and dawn in February and March – Cassiopeia’s Chair dips below the celestial pole. And then this constellation appears to us on Earth more like the letter W.

It’s then that the Lady of the Chair, as she is sometimes called, is said to hang on for dear life. If Cassiopeia the Queen lets go, she will drop from the sky into the ocean below, where the Nereids must still be waiting.

Bottom line: Cassiopeia the Queen is an easy-to-find constellation. It has the shape of a W or M. Look in the north-northeast sky on September and October evenings.

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The post Cassiopeia ascends in September and October first appeared on EarthSky.