# Fomalhaut (Alpha Piscis Austrini)

Fomalhaut (Alpha Piscis Austrini) is a star in the constellation Piscis Austrinus, magnitude 1.2.

**A lonely bright star ringed by dust — and home of a ‘planet’ that turned out to be a cloud of wreckage.**

Fomalhaut is a young white [star](https://astropilot.space/glossary/star), a few hundred million years old, about twice the Sun’s mass and 17 times as bright. Around it lies a vast ring of dust with a sharp inner edge, sometimes called ‘Fomalhaut’s Kuiper belt’. The dust must be constantly topped up: collisions between icy bodies — perhaps 2,000 kilometre-sized comets a day — keep grinding out fresh grains.

In 2008 Hubble images showed a speck just inside the ring, hailed as the first planet candidate ever imaged in visible light. It was named Dagon, after a Semitic god often shown as half-man, half-fish. But the speck spread out and faded, and studies in 2019 and 2023 concluded it was probably an expanding cloud of debris from a collision between two large bodies.

The star’s name comes from the Arabic for ‘the mouth of the fish’: it marks the mouth of Piscis Austrinus, the Southern Fish.

Fomalhaut (Alpha Piscis Austrini) is 25 light-years away: the light we see from it set off in 2001, 5 years before Pluto was reclassified as a dwarf planet.

## Did you know?

- **Far-flung family.** Fomalhaut shares its path through space with two companions, the orange dwarf TW Piscis Austrini and the red dwarf LP 876-10, though they appear about 8° apart in our sky.
- **A measuring stick.** Since 1943 Fomalhaut’s spectrum has served as one of the standard references against which other stars are classified.

A solitary white star in an empty stretch of southern sky, with no other bright star near it. Extend the western side of the Square of Pegasus southwards to reach it. Its isolation makes it easy to identify.

## When and where to see it

It is best placed in the evening sky around October, when it crosses the meridian at about 10 pm local time (around midnight in September). It can be seen from everywhere south of 60°N and never sets south of 60°S.

At its highest it stands 10° up from 50°N, 25° up from 35°N, 60° up from the equator, 85° up from 35°S.

## Facts

- Type: Star
- Constellation: Piscis Austrinus
- Designations: Alpha Piscis Austrini, α PsA, 24 PsA, HR 8728, HD 216956, HIP 113368
- Magnitude: 1.2
- Position: RA 22h 57.6m, Dec −29° 37′ (J2000)
- Spectral type: A4V
- Colour: white (B−V 0.09)
- Distance: 25 light-years
- Discovered: Known since antiquity

Open AstroPilot to see when Fomalhaut (Alpha Piscis Austrini) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/fomalhaut