The National weather outlook for Thanksgiving Day suggests that much of the country will enjoy generally fair weather. The exceptions will be for parts of the Great Lakes where snow showers and flurries will fall, along with perhaps some locally heavy lake-effect snow squalls, especially for northeast Ohio, northwest Pennsylvania, and western and northern New York State. In addition, some light snow may fall over parts of the "Big Sky Country" of Montana and northern Idaho, with rain showers near and along the coasts of Washington and Oregon. Much of the western US will enjoy unseasonably mild weather, while a good part of the eastern US will be experiencing rather brisk and unseasonably cold conditions.

If your household is like most American families, then on Thursday, you likely will all be sitting down with family and friends to a traditional Thanksgiving turkey dinner during the mid-to-late afternoon hours. Then, as darkness falls, some will probably migrate into the living room to catch some football or other holiday fare on television. But if you have a large gathering of family and friends at your home — and if your skies are mainly clear — why not invite everyone outside to gaze at the evening sky?

If you have binoculars, or better yet, a telescope, you just might end up turning this into a memorable family tradition of its own.

The moon, plus a bright planet

As darkness falls on Thursday, there will be the moon shining in the south-southwest, only several hours away from arriving at its first quarter or "half" phase. And located less than 20 degrees — the equivalent of two clenched fists held at arm's length — to its left will be the planet Saturn.

Even in binoculars, the moon is a striking sight to see. It's such a special object because it doesn't matter whether you live in a rural area or in the middle of a brightly lit city, for the moon can always be readily observed. It always looks spectacular whether you're using binoculars or a telescope. It never looks precisely the same, no matter how often you view it, and can be observed even on hazy or partially cloud-covered nights. As it turns out, when the moon is near first quarter, that's just about the best time to look at it for a few reasons:

1. The moon is in a fine position for evening study
2. The moon is not sufficiently bright to cause loss of detail due to glare.
3. As the line of darkness — called the terminator — recedes, features near the border stand out in bold relief; the shadows become stronger and details are more easily seen.

If I may paraphrase the mysterious voice from the 1989 movie, "Field of Dreams": "If you set up your telescope, they will come." And you'll get a big kick out of your Turkey Day guests uttering all the "oohs" and "ahs" or exclamations of "Wow!" just one peek through the eyepiece will get.

Meanwhile, Saturn glows at first magnitude, shining with a sedate, yellow-white glow and appearing slightly brighter than the star Fomalhaut, glowing far to its lower right. Its famous ring system is now tilted only about one-half-degree toward Earth and as a result, it appears most unusual when viewed through the eyepiece of a telescope magnifying over 30-power; just a thin line of light bisecting Saturn's disk.

Stars of late autumn

If we concentrate on the stars and constellations, it is interesting to note that many of the star groups and rich Milky Way fields of summer evenings are still very much evident in the western part of the sky, while the brilliant yellow star Capella ascending in the northeast is a promise of even more dazzling luminaries to come. In just a few weeks, Orion and his retinue will be dominating our winter skies.

Still very well placed high in the west is the "Summer Triangle," a roughly isosceles figure composed of the stars Vega, Altair and Deneb. As we move deeper into the autumn season and the evenings grow all the chillier, this configuration sinks lower and lower in the west. If you have binoculars, invite family and friends to use them to sweep among the splendid star fields of the Summer Triangle. They may very well share Galileo's awe when, more than four centuries ago, he first turned his telescope on the myriads of faint stars that compose our Milky Way.

Looking high in the south-southeast — almost overhead — are the four bright stars that compose the Great Square of Pegasus, a landmark of the autumn sky. And if you have a clear view of the northern horizon, it is there where you will find the familiar Big Dipper, looking abnormally large due to the "moon illusion" which makes both the sun and the moon and even star patterns like the Dipper, appear larger-than-normal when they are situated near to the horizon. Meanwhile, the striking zig-zag row of five bright stars forming the "M" of Cassiopeia, the Queen, soars high above the Dipper in the north.

Looking back in time

The very first Thanksgiving is said to have taken place in the year 1621. We see many stars by light that started its immense journey before our country was born. Are there any stars that are around 400 light-years away? Because of the difficulty in measuring parallaxes (distant objects' changing positions when viewed from Earth), astronomers cannot determine such distances with an accuracy of one light-year. However, the 2025 "Observer's Handbook" of the Royal Astronomical Society of Canada, in its table of 288 brightest stars, lists two that are above the horizon on November evenings that are 400 light-years away: Third-magnitude Algenib, the star in the lower left corner of the Great Square of Pegasus, and second-magnitude Almach, at the end of the chain of stars marking the constellation of Andromeda, the princess. If you see either of these stars on your next clear night, keep in mind that you are looking at light that started on its journey to Earth about the same time that the first pilgrims were arriving in what we now call the state of Massachusetts.

Here at Space.com, we like to wish a very happy and safe Thanksgiving to all, and of course, clear skies!

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky & Telescope and other publications. Follow us on Twitter @Spacedotcom and on Facebook.

As night falls on October evenings, glance toward the southeast horizon. If there is one star that serves to announce the arrival of fall as the leaves have begun to turn, unquestionably that title would have to go to the brightest star within an otherwise dim and obscure star pattern.

That star pattern is Piscis Austrinus the Southern Fish, which resides to the east and south of the zodiacal constellations of Capricornus the Sea Goat and Aquarius the Water Bearer. It's a V-shaped figure of five stars; faint stars that in most cases, cannot be seen from mid-northern latitudes, for even when they are at their highest above the southern horizon, they are still too low to penetrate the ground haze.

The lone star in question however, that is readily visible is Fomalhaut. While there is excellent authority for calling it "Fo'ma-lo," as if it were a French word, the name is actually a corruption of the Arabic Fum al Hut, meaning the "Mouth of the Fish." As such, it might better be pronounced "Fo'mal-hawt."

Practically by itself

Look for it this week low toward the south at around 9:30 p.m. local daylight time. If you need help locating it, consider using a smartphone astronomy app.

Shining at magnitude +1.2, this bluish-white star is relatively close by at only 25 light-years away. It's almost twice as large as our sun and is about 16 times as luminous. Fomalhaut is also part of a multiple star system, with two other fainter companion stars.

Some 2 degrees of arc (0.03 of a degree) southward from it, is a magnitude 6.5 dwarf star that seems to be sharing Fomalhaut's motion through space. They are so far apart that it is hard to call them a binary system. Maybe these two stars are all that is left of a cluster that dissipated long ago.

But while it is not an overly bright star, it manages to stand out because it's the only truly bright star that dominates a considerably dull area of the sky around it. Thus, it is easily seen and identified and is of great interest and value to navigators.

As such, Fomalhaut is often referred to as "The Solitary One," primarily because it lies in such an empty region of the southern autumn skies. For those living at mid-northern latitudes like New York, Chicago and Denver it is the southernmost of the visible first magnitude stars. Acclaimed popular science writer Fred Schaaf notes that this star, "Stands like a lonely lighthouse beacon near the shore of the Great Celestial Sea of water constellations."

Martha Evans Martin wrote a popular guide to the night sky in 1907 (revised several times since) called "The Friendly Stars." Of Fomalhaut, she wrote: "The loneliness of this star, adds to the somber signs of approaching autumn, and sometimes gives one a touch of melancholy."

Stellar aristocracy

Five thousand years ago in Persia, there were four stars that each ruled over its particular quadrant of the sky. They were deemed "Royal Stars" that had the privilege of being among the guardians of heaven, and Fomalhaut was one of the chosen four. The other three were Aldebaran, in Taurus; Regulus in Leo; and Antares in Scorpius.

Draw a line between the two bright stars marking the right side of the Great Square of Pegasus (Scheat and Markab) and extending that line downward nearly four times the distance between those two stars will bring you to Fomalhaut.

Home to a planet ... or comets?

Interestingly, in November 2008 astronomers using the Hubble Space Telescope announced that they had apparently discovered an extrasolar planet orbiting Fomalhaut, possessing nearly three times the mass of Jupiter. However, more recent analyses of existing and new observations utilizing the Spitzer Space Telescope indicate that the supposed planet may actually be nothing more than a knot of material within in an expanding, swirling disk — possibly a belt of comets — composed of gas and dust, that encircles Fomalhaut.

A little fish's claim to fame

Many of the old-time allegorical star atlases from the 17th and 18th century depicted the Southern Fish as a long, slim fish with an open mouth and usually shown drinking the water that was being poured from the great urn of Aquarius; no mean achievement for such a small creature.

That seemingly is what makes Fomalhaut so special; it's got a big personality for such a small fry.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope and other publications.

Late October presents a perfect opportunity to spot the ancient light of the Andromeda galaxy as it climbs high overhead to brighten the autumn night sky.

The Andromeda Galaxy (M31), the Milky Way's closest galactic neighbor, sits approximately 2.5 million light-years from Earth in the constellation Andromeda. It can be found rising in the east at sunset before drifting high overhead at midnight and transitioning to the northwestern sky as dawn approaches.

Andromeda's vast spiral arms span an incredible 260,000 light-years across and play host to over a trillion stars, all orbiting a supermassive black hole embedded in the galactic core, which glows with the light of ancient red stellar bodies.

Andromeda is easily visible to the naked eye from a dark sky location, taking the form of a hazy oval blur, while a telescope or binoculars will help reveal the light from its active glowing core surrounded by a diffuse haze of milky light.

How to find the Andromeda galaxy

First, locate the 'M' star formation of the constellation Cassiopeia, which appears high overhead at midnight for viewers in the U.S. The leftmost three stars will form a pointer with the bright stellar body Shedar at its tip, guiding the way to the Andromeda Galaxy

A favorite target for astrophotographers

The Andromeda galaxy is a perennial favorite among astrophotographers, who devote vast amounts of time and energy to collecting Andromeda's faint light and processing it into breathtaking galactic portraits.

One standout example comes from Ronald Brecher, who spent a grand total of 38 hours imaging Andromeda in August and September earlier this year to reveal a wealth of star formation brightening spiral arms choked with cosmic dust.

Thanks to smartphone astrophotography, anyone can now capture impressive shots of galaxies and nebulas. All you need is a phone, a telescope and an inexpensive smartphone adapter to align the camera with the eyepiece.

Smartphone astronomy advocate Jim Preusse captured a stunning view of the Andromeda galaxy using a Pixel 9 Pro smartphone camera mounted over a 56 mm eyepiece on his Orion XT 10G telescope.

"The great thing about smartphone astrophotography is that anyone can do it," Preusse told Space.com in an email. "The results are quick so you are able to view several targets in one evening. Whether viewing old favorites or new, each time out is an adventure with something new to see."

Using just a 4-minute exposure in the Pixel 9 Pro's Astro Mode, Preusse's image revealed Andromeda's bright core and sweeping dust lanes in its spiral arms. The small satellite galaxy M32 is also visible as a glowing ball to the upper left of Andromeda's core, while elliptical galaxy Messier 110 is visible below its hazy disk.

Interested in capturing the post sunset realm for yourself? Then be sure to check out our beginners guide to astrophotography, along with our roundups of the best cameras and lenses for photographing the night sky.

Astrophotographer Brennan Gilmore has captured spectacular views of the solar wind stripping a vast section from C/2025 A6 (Lemmon)'s tail, as the icy wanderer continues to brighten ahead of its close approach to Earth on Oct. 21.

Comet Lemmon has brightened dramatically since its discovery on Jan. 3,, raising hopes that it could become a spectacular naked eye comet in October as it nears the closest point to the sun in its 1,350-year orbit on Nov. 8 — a point known as perihelion.

Gilmore's image gives us a spectacular view of Comet Lemmon's glowing green coma as it passed close to the bright star TW Leonis Minoris in the constellation Leo Minor on Oct. 4. A long luminous tail stretches away from the comet's nucleus, as material ejected from the comet reflects the light of the nearby sun.

A comet's tail is constantly being blown by the steady stream of charged particles emanating from the sun collectively as the "solar wind". As such, it will always point away from the sun, rather than simply trailing a comet's direction of travel, like the exhaust trail of an aircraft.

Gilmore released a stunning 60-minute timelapse of Comet Lemmon as a colossal section of its tail was buffeted and stripped away by the solar wind on Oct. 2, during a spectacular disconnection event. The images were taken using a Takahashi Epsilon 130D Newtonian telescope in conjunction with a ZWO astronomy camera from Cismont, Virginia.

Comet Lemmon continues to brighten, with some observations posted by the Comet Observation Database (COBS) run by the Crni Vrh Observatory in Slovenia, putting its brightness at +5.1, which would make it detectable as an extremely dim object to the unaided eye from a dark sky location.

Be sure to check out our finder's guide if you're hoping to lay eyes on Comet Lemmon as it brightens further in October and read our tips on how to photograph a comet if you want to create a permanent memory of the wandering body before it disappears from our skies,

Editor's Note: If you would like to share your astrophotography with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

The autumn equinox is now upon us! Today marks the moment that the sun crosses the celestial equator, ushering in the beginning of astronomical autumn in the northern hemisphere, which brings with it the inevitability of longer nights, perfect for stargazing.

In 2025, the autumn equinox will occur on Sept. 22 at 2:20 p.m. EDT (1820 GMT), when the sun moves southward across the celestial equator. The celestial equator is an imaginary projection of Earth's equator into space, forming a circle around the sky that divides the northern and southern celestial hemispheres. The sun's drop across the equator is due to a 23.5° tilt in Earth's rotational axis, which shifts our star's apparent path in the sky as our planet goes about its yearly orbit.

We experience two equinoxes each year, one in March and one in September, when the tilt of Earth is such that the sun shines equally on the north and south hemispheres. During an equinox day and night boast a roughly even 12-hour duration. It is for this characteristic that the name equinox was derived, from the Latin words "aequus" (equal) and "nox" (night).

On the day of the 2025 autumnal equinox, the sun rises almost exactly due east and sets to the west. The months that follow will see cooler temperatures set in as the northern hemisphere receives less direct sunlight, while the nights will grow longer and darker — a trend that will continue until we celebrate the winter solstice on Dec. 21.

While Sept. 22 marks the beginning of autumn in the northern hemisphere, the exact opposite is true south of the equator, where spring is about to begin in earnest!

Dark, long autumn and winter nights are the perfect time to indulge in some astronomy. Be sure to check out our roundup of the best telescopes and binoculars available in 2025 to ensure that you're ready to explore the changing skies.

Those interested in capturing the post-sunset realm should also read up on our selection of the most capable cameras and lenses for astrophotography, as well as our guide to photographing the moon as its seasonal path takes it higher in the night sky in the coming months.

Editor's Note: If you would like to share your astrophotography with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

Autumn officially arrives in the Northern Hemisphere on Tuesday, Sept. 22 at 9:31 a.m. EDT (1331 GMT). And consequently, our evening sky is now one in transition. 

Many of the striking star groups and rich Milky Way fields of a summer evening still remain with us in the western sky, while the brilliant star Capella ascending in the northeast is a promise of more luminaries to come. 

Just think of this: two months from now, the constellation of Orion, the hunter and his retinue will be dominating our evening skies; forerunners of the oncoming winter season.That of course leaves us to talk about the stars of fall, but before we get into that, some lingering thoughts about our current evening skies.

Related: Why the night sky changes with the seasons 

Smoky skies

In the northern United States, football weather usually brings many clear, dry nights with far better observing conditions than are typically of summer. In this seemingly dysfunctional year of 2020, however, we've had to cope nationwide with airborne smoke from the wildfires in the western states. Even in the Northeastern States and New England, high altitude smoke on some nights has squelched all but the brightest stars and planets. 

We can only hope that in the coming days, that this widespread smoke and haze layer (can we refer to it as "smaze"?) will gradually dissipate and allow for clearer and more transparent night skies. When that happens, why not explore with binoculars the splendid star fields within the famous asterism (or star pattern) known as the Summer Triangle? Sweep especially along the neck of the constellation of Cygnus, the swan, which is also the upright of the Northern Cross asterism. In fact, the brightest part of the Milky Way can be found from here, extending down through the constellation of Aquila, the eagle and down to the "Teapot" of Sagittarius, an asterism that marks the center of our Milky Way galaxy. 

If you have never done this before, you may well share Galileo's awe when more than four centuries ago he turned his first crude telescope on the Milky Way.

Watery stars

In contrast to the bright and pretty star fields of the summer Milky Way now slowly departing the scene in the west and the array of bright stars of winter beginning to make themselves evident in the east, we have the stars of autumn largely predominating our sky across much of the south. We might refer to this region of the sky as the "celestial sea" because so many of the star patterns seem to have an association with water. From west-to-east, we have a sea goat (Capricornus), a water carrier (Aquarius), a pair of fishes tied by their tails to a fishing line or ribbon (Pisces), yet another fish placed far to the south (Piscis Austrinus), a whale (Cetus) and a winding river (Eridanus).

Indeed, it is a "watery region" of the sky.

British astronomer and author Guy Ottewell, in his book "To Know the Stars" (Astronomical Workshop, 1990), goes even further in this analogy: "It is watery in the sense that it is vague and dim, like a dark pool; they are all dim and hard to recognize." 

Indeed, with the exception of the southern fish asterism, Piscis Austrinus, which contains one lone star of first magnitude, a preponderance of all of the stars in this region of the sky are of magnitudes 3, 4 and 5. Magnitude is a way that astronomers classify the brightness of sky objects, with the lower the figure of magnitude, the brighter the object. The brightest stars, for example, are either magnitude 0 or +1. If you live in a bright city or nearby suburb, your limiting magnitude might only be +3. Any star with a value higher than that might not be visible at all, hence giving the impression that the sky during the fall is practically devoid of bright stars. 

One outstanding exception is glowing brilliantly with a yellow-orange light in the eastern sky soon after 10 p.m. in your local time. This interloper is shining among the dim stars of Pisces, the fishes at a negative magnitude of 2.3. This is the planet Mars, which is now making an exceptionally close approach to Earth. The Red Planet reaches perigee, or its closest point to Earth all year, on Oct. 6. We'll have more to say about this next week. 

A contorted constellation

The ancients who had conceived the watery constellations must have had a very vivid imagination. Capricornus is an excellent example of this. A centaur is a half man and half horse, and a mermaid is a half woman and half fish. In Capricornus, now about halfway up in the southern sky at 9 p.m., we supposedly have a half goat and half fish, though its dim stars form a roughly triangular figure which might better suggest an inverted hat, or perhaps a sting-ray gliding toward you. At this moment in time, the western end of the sea goat is occupied by a bright yellow-white "star" which is really the planet Saturn. In late December, brighter Jupiter will shift east and will nearly merge with Saturn in what is being promoted as "The Great Conjunction," which will happen in Capricornus. 

Several thousand years ago, the sun reached its southernmost position in the sky (the winter solstice — declination 23.5 degrees south) when it was passing through Capricornus. During this time, it was overhead at a southerly latitude we call the Tropic of Capricorn. It still carries this name although the sun, as a result of a long-term wobble of the Earth's axis, is now in Sagittarius at the time of the winter solstice. 

The Water Man and his fish

I sometimes wonder how many who hear the popular song "Aquarius" (by The 5th Dimension) know what Aquarius really is. It is a zodiacal constellation which traditionally represents a man holding a water jar or urn (marked by an inverted "Y"-shaped asterism of four stars), which is spilling a vaguely marked stream of water southward into the mouth of Piscis Austrinus, the southern fish. 

Here we find a somewhat isolated first-magnitude star, Fomalhaut. The name is really a corruption of the Arabic Fum al Hut, meaning the "mouth of the fish." As such, it might best be pronounced "Fo'mal-hawt." Because it seems to sit all by itself, low in the southern sky this week at around 11 p.m., Fomalhaut is the star often referred to as the "Lonely One."

Another pair of fish form the stretched-out zodiacal group known as Pisces; two fishes, each tied on the end of a ribbon or string, knotted together at the ends. The western fish has a circular shape called the Circlet and the eastern fish resembles a small, faint triangle. Perhaps we could call the western fish a flounder or fluke while the eastern fish might represent a trout or herring. As we noted, Mars is currently blazing in Pisces, calling attention to this rather faint star pattern. 

A "wonderful" star!

Sprawling to the south and east of the fishes is Cetus. Some astronomy books refer to him as a whale, and indeed the name is derived from the Latin "Cetacea," meaning whale. Other reference sources refer to Cetus as a sea monster. 

Some allegorical star atlases depict him as resembling a Godzilla-like creature with a fish tail. Cetus is best known for Mira, a special reddish star which is located not far southeast of where the ribbons of the fishes are knotted. Mira is the very first variable star to be discovered. On Aug. 13, 1596, the German astronomer David Fabricius caught sight of it where no star was charted before. It soon faded away and so it was thought that it was a nova, or exploding star, never to be seen again. And yet, when Johannes Bayer mapped the constellations in 1603, the star was visible once again and quite unaware of its "now you see it, now you don't" behavior, Bayer listed it in his famous atlas as Omicron Ceti. 

Finally, during the winter of 1638, the Dutch observer Johannes Holwarda caught both the gradual brightening and subsequent fading of this star, almost like a leisurely celestial lighthouse. It seemed to grow brighter, then fainter, then brighter again over a roughly 330-day (11-month) cycle. It seemed to rise to its greatest brilliance twice as fast as it fades to below naked-eye visibility. The noted Polish astronomer Johannes Hevelius christened it Mira Stella, the "Wonderful Star" in 1662. At its faintest, Mira shines only as bright as a ninth magnitude star and is visible only with a small telescope. 

At its brightest, Mira appears 250 times brighter, usually equal to a third-magnitude star, though on rare occasions it can get even brighter and in one year (1779) it became so bright that it nearly rivaled the first-magnitude star Aldebaran in the constellation of Taurus, the bull. 

This week, Mira is forecast to be shining at its peak brightness, so why not check it out and see how bright it is shining? Cetus is well up in the southeast part of the sky in the hour before midnight and covers a large part of the southern sky by 2 to 3 a.m.

A meandering celestial stream 

Lastly, there is the Heavenly River, Eridanus, a constellation that at this time of year does not begin emerging from beyond the southeast horizon until after midnight. It has been visualized as a river since ancient times — usually the Euphrates or the Nile. 

It begins near the brilliant blue star Rigel in Orion and flows in a general southwest direction; a winding stream of dim stars whose meanderings may not be able to trace without the aid of a map. It ends in a blaze of glory with Achernar, a blue first-magnitude star glowing at the end of the river, but unfortunately, out of sight except when it grazes the southern horizon in the southernmost United States. 

Too bad! You might say Achernar is "out of the mainstream," so to speak. 

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook. 

Around 3000 B.C., during the time of the ancient Persians in what today we would call Iran, there were four "royal stars" in the nighttime sky. Presumably, in accordance with Persian culture, the sky was divided into four districts with each district being guarded by one of these four special stars. 

All four were first-magnitude stars — among the 21 brightest stars in the sky — which was apparently a prerequisite for being designated as "royal," or one of the symbolic, stellar guardians of the heavens.

Another apparent prerequisite, was that these stars needed to be close to the ecliptic, that imaginary line in the sky along which the sun, moon and five naked-eye planets appear to follow. That line also passes through the 12 constellations that compose the signs of the zodiac. 

Related: Happy Equinox! It's the 1st Day of Autumn in Earth's Northern Hemisphere

Three of these stars met the proper requirements: the bright, orange star Aldebaran in the constellation Taurus (the bull), the bluish star Regulus in Leo (the lion), and the ruddy star Antares in Scorpius (the scorpion). 

But for the fourth district, the one that encompasses our current evening sky for autumn, there was a problem in that there was no bright star present along the ecliptic. The most noteworthy zodiacal star patterns of autumn included Capricornus (the sea goat), Aquarius (the water carrier) and Pisces (the fishes). Indeed, this region of the sky is popularly known as the "celestial sea" and is a wide, dark area devoid of bright stars and composed of star patterns that all have an association with water. Capricornus, Aquarius and Pisces are three constellations that contain stars no brighter than third-magnitude ... and many more are actually in the much fainter fourth- and fifth-magnitude category. 

So, in order to designate a fourth (bright) "royal star" candidate, the ancient Persians begrudgingly had to find a star that was not in the zodiac. They finally came up with Fomalhaut, the 18th-brightest star in the sky, in the modern constellation of Piscis Austrinus (the southern fish). 

A stellar eremitic

Sometimes referred to simply as "The Solitary One," Fomalhaut stands out in what is otherwise a rather empty region of the autumn sky. In her 1907 book, "The Friendly Stars," Martha E. Martin wrote: 

"On early acquaintance, the loneliness of this star, added to the somber signs of approaching autumn, sometimes giving one a touch of melancholy."

With these words, Fomalhaut certainly can be considered to be the star that announces the arrival of fall.

For those living at mi-northern latitudes, such as New York, Chicago and Denver, it is the southernmost of the visible first-magnitude stars, never climbing more than about 20 degrees above the southern horizon at its highest. Your clenched fist held at arm's length measures 10 degrees, so Fomalhaut, at best, gets only about "two fists" above the horizon. 

To make a positive identification, this week around 9:30 p.m. local time, look high in the southeast sky for one of the landmarks of autumn: the Great Square of Pegasus. Trace an imaginary line along the western (right hand) side of the Square and extend that line about 3.5 times that distance, and there you will find Fomalhaut. There are no bright stars along the way; you'll be passing through the dim regions of Pisces and Aquarius. In fact, the water pouring from the water jar that is held by Aquarius consists of some ill-defined lines of stars stretching south. And it is near the end of one of these lines that we come to Fomalhaut. 

Piscis Austrinus was often pictured in many old star atlases as a long, slim fish with an open mouth and is usually depicted drinking the water that flows from the water jar of Aquarius. 

This would make some sense, since Fomalhaut is really a corruption of the Arabic "Fum al Hut," meaning "mouth of the fish." Some believe that Fomalhaut symbolizes the New Testament story of St. Peter and a coin (a tetradrachm) found in the mouth of a fish. 

Fomalhaut is situated 25 light-years away from Earth — close by stellar standards — and is nearly twice as large and as massive as our sun. It is also nearly 17 times more luminous and shines with a white color, although more than a few constellation guidebooks refer to it as appearing with a reddish hue. This is probably because it appears rather low in the sky, that the haze that often lurks near the horizon attenuates its light and tends to give it a somewhat ochre hue. 

Fun facts about Fomalhaut

Three other things make Fomalhaut a most interesting star. 

First, Fomalhaut is relatively quite young, only about 440 million years old. In contrast, our sun is estimated to be about 5 billion years old. Because Fomalhaut is hotter and brighter than our sun, it also has a shorter life span of somewhere around 1 billion years. Stars like the sun have life spans of about 10 billion years.

Second, is that Fomalhaut is surrounded by several regions of dense gas and dust, which astronomers refer to as a protoplanetary disk. Near the outer edge of this disk, in November 2008, the Hubble Space Telescope captured an image of an object believed to be an extrasolar planet orbiting Fomalhaut. The planet in question is estimated to be about three times as large as Jupiter, yet only as massive as Neptune. Some believe that this might not be a planet at all, but merely a gravitationally bound accumulation of rubble. 

Third, there is a faint (magnitude +6.5) dwarf star, known as TW Piscis Austrini, located about 2 degrees to the south, that appears to be sharing Fomalhaut's motion through space. This star shines with less than 20% of the luminosity of our sun, but is so distant — nearly 1 light-year from Fomalhaut — that it's difficult to call them a binary star system. Some speculate that these two stars are the sole remnants of a low-density star cluster that dissipated long ago. 

Believe it or not, an extrasolar planet might also be circling TW Piscis Austrini. NASA's Transiting Exoplanet Survey Satellite (TESS), a space telescope that's searching for planets around the brightest stars in Earth's night sky, recently found a possible candidate circling this star. It's almost the same size as our Earth, and orbits the star about every 10 days at a distance of 7.5 million miles from it. However, more observations are needed to confirm whether the exoplanet really exists. 

Finally, aside from Fomalhaut, the stars that make up the rest of the southern fish are — no surprise — dim and hard to see. Perhaps this makes Piscis Austrinus a shy fish. 

That, or he's very koi.

• The Stars of Autumn's Night Sky: What to Look For
• Why the Night Sky Changes With the Seasons
• How Bright Are the Stars Really?

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications, and he is also an on-camera meteorologist for Verizon FiOS1 News in New York's lower Hudson Valley. Follow us on Twitter @Spacedotcom and on Facebook.

In early October, the mid-evening (9 to 10 p.m.) sky is in transition.

Many of the constellations and rich Milky Way star fields of summer evenings past are still very much in evidence in the western heavens, while the brilliant yellow-white star Capella ascending from low in the northeast is a promise of even more dazzling stars to come. In another couple of months, Orion and his retinue will be dominating the eastern sky as we approach the start of another winter season.

Still very well placed for viewing high in the southwest sky is the famous "Summer Triangle," a large, roughly isosceles figure composed of three of the 21 brightest stars in the sky: Vega, Altair and Deneb. [Night Sky: Visible Planets, Moon Phases & Events, October 2013] 

Interestingly, at this time of year, the stars still maintain their steady drift westward and set four minutes earlier each night, but this is somewhat compensated by the fact that darkness is coming rapidly earlier every night – during October as seen from mid-northern latitudes, the sun is setting about 1 1/2 minutes earlier each night, so the star positions appear to be only slightly displaced.

Case in point: The position of the stars at 9:30 p.m. local daylight time this week will have changed little as seen at 6:30 p.m. local standard time during the first week of November. It might seem odd that a star pattern so closely identified with balmy summer nights is still in plain view high in the sky at nightfall on chilly mid-autumn evenings, but take advantage of these circumstances. Unlike the summer, when nights are often hazy across the northern tier of the United States, football weather brings many clear, crisp nights with far better observing conditions.

A milky split

Using binoculars, try sweeping through the Summer Triangle and explore the beautiful star clouds of the "summer" Milky Way. 

From a location far from the glare of bright city lights, the view of this section of the sky is nothing short of breathtaking. Try to take it all in with just the naked eye and you’ll soon become aware of an enormous dark lane running south along the Milky Way from Deneb and then practically midway between Vega and Altair.

This is the famous splitting or "bifurcation" of the Milky Way, which provides clear evidence that some parts of interstellar space are far from transparent. The split is caused by thick clouds of interstellar dust positioned along the plane of our galaxy. Such clouds that are so dense that they cut off our view of more distant bright objects are sometimes referred to as dark nebulae.

The neck of the constellation Cygnus (The Swan) runs straight on down through the bifurcation. Cygnus is also popularly referred to as the Northern Cross; the neck of the Swan also serves as the upright of the Cross. Deneb marks the top of the upright, while at the foot of the Cross is a much dimmer star known as Albireo. 

I went into greater detail about this star a few months back, but since it’s still in good viewing position, I again urge you to check it out with binoculars or a small telescope; optical aid reveals it to be in actuality a beautiful double star. Look particularly at the striking color contrast between the two components: orange for the primary and diamond blue for the companion.  

Speaking of autumn

Of course, since it is autumn there are a number of much dimmer stars of the fall season that cover much of the southern and eastern sections of the sky. 

The dim zodiacal constellation Aquarius is very much in evidence over in the southern sky. This star pattern traditionally represents a man holding a water jar (marked by an inverted Y-shaped group of four stars), which is supposedly spilling a vaguely marked stream of water southward into the mouth of Piscis Austrinus, the Southern Fish. 

Here we find a somewhat isolated 1st-magnitude star, Fomalhaut, whose identity can be definitively checked by extending a line along the western (right) side of the Great Square of Pegasus about three times its own length. 

Fomalhaut announces the arrival of autumn. When you see it hanging low near the southeast horizon at nightfall at this time of year, the turning (and falling) of the leaves have begun. 

And when you see Fomalhaut already beginning to sink in the southwest by nightfall in late November, it usually means that the leaves have stopped falling . . . and fall starts leaving.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.