EarthSky | Fomalhaut, the loneliest star, close to Jupiter and Saturn in 2021


In northern autumn 2021, the brilliant, solitary star Fomalhaut will seem close to the brighter planets Jupiter and Saturn. Look southward from the Northern Hemisphere. Look excessive within the sky (in southern spring 2021) from the Southern Hemisphere.

Fomalhaut, brilliant and lonely

Fomalhaut, aka Alpha Piscis Austrinus, is usually referred to as the Loneliest Star. That’s as a result of it’s the one brilliant star in a large stretch of sky. From the Northern Hemisphere, Fomalhaut arcs in solitary splendor throughout the southern sky in autumn. Some name it the Autumn Star. From the Southern Hemisphere, you’ll look increased as much as see Fomalhaut in your season of spring. In 2021, Fomalhaut isn’t so solitary. Two brighter planets, Jupiter and Saturn, seem close to it within the sky. Fomalhaut would be the one which’s twinkling.

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Keep studying to study extra about this younger star. It’s of particular curiosity to astronomers as a result of it has a particles ring round it. Astronomers assume new worlds are forming in Fomalhaut’s ring, at an early stage within the planet-forming course of.

How to see it

Fomalhaut is the 18th brightest star within the night time sky. It’s a part of the faint constellation Piscis Austrinus, the Southern Fish. In a dark sky, you’ll see a half-circle of faint stars of which brilliant Fomalhaut is a component. This star sample marks the open mouth of the Southern Fish.

In early September, Fomalhaut is kind of reverse the sun. And so it shines within the sky all night time. It reaches its culmination – its highest level within the sky – round native midnight in mid-September.

Fomalhaut culminates (reaches its highest level within the sky) at completely different occasions on completely different dates. Here are only a few approximate occasions and dates of end result:

July 15: 4:30 a.m. daylight saving time (DST)
August 15: 2:30 a.m. DST
September 15: 0:30 a.m. DST
October 15: 10:30 p.m. DST
November 15: 8:30 p.m. DST
December 15: 5:30 p.m. customary time

From the Northern Hemisphere, you may see Fomalhaut from as far north as 60 degrees latitude (southern Alaska, central Canada, northern Europe), the place it simply skims the southern horizon. From the Southern Hemisphere, Fomalhaut seems a lot increased within the sky. You can use one in every of a number of stargazing smartphone apps, some which might be free, that will help you discover it. Or go to, the free on-line planetarium, and enter your location and time.

A gray, black, and white star chart (with stars represented as black dots).
Stars in Piscis Austrinus, the Southern Fish, together with Fomalhaut. Image through International Astronomical Union/ Sky & Telescope/ Wikimedia Commons.
Stars in black sky. Labeled constellations are shown with blue lines connecting the stars.
View larger. | A large view of the sky from Austin, Texas, half-hour previous midnight as it is going to be on September 15, 2021. Fomalhaut, marked on this chart with crosshairs, is roughly 30 levels above the horizon at its highest altitude. (From Washington, D.C., the star can be about 21 levels above the horizon, and in Montreal, Canada, round 15 levels.) To get your bearings, find the nice sq. of Pegasus; use the west aspect of the sq. to information you south, about 3 times its size, towards Fomalhaut. Image through the Stellarium app.

Rings of dust and gasoline

Fomalhaut is a sizzling blue star about 25 light-years away. It’s nearly twice the mass and measurement of our sun however radiates over 16 occasions the sun’s power. Fomalhaut has a companion star lower than a light-year away from it. The companion is a yellowish-red star, about 70% the mass of our sun. A 3rd member of the Fomalhaut star system was announced in 2013, a small reddish star about 2.5 light-years from Fomalhaut. From Earth, we see the third star situated within the constellation Aquarius as a substitute of Piscis Austrinus.

Fomalhaut itself is a younger star, simply 440 million years outdated. That’s in distinction to 4 1/2 billion years for our sun. Fomalhaut is of particular curiosity to astronomers as a result of it has a number of rings of dust and gasoline round it, early indications of planets within the technique of formation round this star. Astronomers have detected interior particles disks near the star, inside a few astronomical models (AU) from the star.

There’s a a lot bigger, thicker particles ring about 133 AU from the star. A study revealed in 2008 generated lots of pleasure when Hubble Space Telescope photographs, taken in 2004, 2006 and 2008 confirmed an obvious planet very near this particles ring. Astronomers first thought it was the primary straight imaged exoplanet. But knowledge from different telescopes introduced that conclusion beneath scrutiny. And, by 2014, this object was not seen to Hubble.

What occurred? Astronomers assume that the “planet” was truly a large dust cloud generated by the collision of two giant our bodies close to the ring. And over time, that dust cloud could have dissipated. Even although it turned out not to be a planet, astronomers had been happy. Catching the aftermath of a collision in a planet-forming disk was good, too! The occasion supplied clues to a deeper understanding about how planets type.

Two images. On the left a dark circle with a red ring around it. On the right a series of bright dots.
On the left, a Hubble Space Telescope picture exhibiting Fomalhaut’s particles disk. The star itself has been blocked so its brightness doesn’t drown its faint ring from view. The small field reveals the thing as soon as considered the planet (however no extra). On the appropriate is a simulation, based mostly on observations, of how the thing appeared from 2004 to 2014. The object is now considered the results of a collision in the disk. Image through NASA.

Fomalhaut in historical past and mythology

The title Fomalhaut derives from the Arabic Fum al Hut, that means Mouth of the Fish.

In the sky seen from the Northern Hemisphere, the constellation Aquarius the Water Bearer resides above Fomalhaut’s constellation Piscis Austrinus. You can see a zigzag line of stars from Aquarius to Piscis Austrinus. In sky lore, this line of stars represents water from the Jar of the Water Bearer, trickling into the open Mouth of the Fish.

According to Richard Hinckley Allen, Fomalhaut was one of many 4 guardians of the heavens to the traditional Persians, in 3,000 BCE, referred to as by them Hastorang. (The different guardians had been Aldebaran in Taurus, Antares in Scorpius, and Regulus in Leo.) Around 2,500 BCE, Fomalhaut helped mark the placement of the winter solstice, that means that it helped to outline the placement within the sky the place the sun crossed the meridian at midday on the primary day of winter. Allen additionally says that in 500 BCE, Fomalhaut was worshipped on the temple of Demeter in Eleusis, in historical Greece.

Fomalhaut’s place is RA: 22h 57m 39s, Dec: -29° 37′ 20″.

Antique etching of an old man carrying a water jug. Below him is a fish. Stars are scattered over the chart.
View larger. | Aquarius the Water Carrier seems above Piscis Austrinus, the Southern Fish, within the Celestial Atlas by Alexander Jamieson, revealed in 1822. In the illustration, water from the Water Jar of Aquarius might be seen going into the Mouth of the Southern Fish. if it’s darkish the place you might be, you may simply see a zigzag line of stars representing this circulate of water. Image through United States Naval Observatory Library.
A darkened skyline, with smoke from a chimney blowing sideways and a single star, Fomalhaut, above.
View larger. | Fomalhaut is usually referred to as the Loneliest Star as a result of no different brilliant stars shine close to it within the sky. Photo by EarthSky Facebook good friend Tony Gieracki. Thank you, Tony!

Bottom line: Fomalhaut is comparatively simple to identify because it shines brightly in an space of sky with no different brilliant stars close by. It is of particular curiosity to astronomers due to particles rings round it, the beginnings of a planetary system.

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