Fomalhaut

Where the name comes from

Fomalhaut comes from the Arabic fum al-hut, the mouth of the fish, where the stream poured by Aquarius the water bearer was imagined to end. It marks the mouth of Piscis Austrinus, the southern fish.

The lonely one

Fomalhaut stands out because of where it is not. It sits in a wide, dark stretch of autumn sky with no other bright stars near it, which earned it the nickname the Lonely Star of Autumn. It is close, about twenty five light years away, and is wrapped in a huge ring of dusty debris, the kind of disk from which planets are born.

A planet that was not there

In 2008 astronomers announced that the Hubble Space Telescope had photographed a planet inside Fomalhaut’s dust ring, one of the first exoplanets ever seen directly. Over the following years the object faded and spread out, and by 2020 many astronomers concluded it was not a planet at all, but an expanding cloud of dust from a collision between two smaller bodies. Science changed its mind in public, which is how it is meant to work.

How to find it

From the northern hemisphere, look low in the south on autumn evenings, below the Great Square of Pegasus. The two stars on the square’s western side point down toward it. It is the only bright star in that whole region, at about magnitude 1.2 in the catalogue Hali uses, so if you see one bright point low in the south in October, it is almost certainly Fomalhaut. From the southern hemisphere it rides high overhead.

Fomalhaut in a chart

By Hali’s 2026 star positions Fomalhaut sits at 4 degrees of the sign Pisces, and the Sun reaches that degree around 22 February each year. Ptolemy gave the bright star at the mouth of the southern fish the nature of Venus and Mercury. Modern books often call it one of the four royal stars of Persia, with Aldebaran, Regulus and Antares, though the ancient source for that grouping is uncertain. Astrologers who use fixed stars read a planet on it as idealism and imagination.

Common confusions

Fomalhaut is not in the zodiac constellation Pisces, the two fish. It belongs to Piscis Austrinus, the southern fish, a separate and much smaller constellation below Aquarius. The similar names and its zodiac degree in the sign Pisces make the mix-up easy.