Fomalhaut

Fomalhaut is a white star, hotter than the Sun, in the constellation Piscis Austrinus. It is in the long, steady part of its life, making helium from hydrogen in its core, as the Sun is.

Fly to it in 3D Find it on the sky map

A drawing in the star's own colour, worked out from its measured colour index. It is not a photograph.

How far

25 light years

The light you see from Fomalhaut tonight set off about 25 years ago. Everything we know about it is that much out of date.

How bright

18 Suns

It gives out 18 times as much visible light as the Sun. From the Earth it is the 18th brightest star in the night sky. It is one of the brightest stars in the whole sky, easy to see even from a town.

Astronomers put its brightness in our sky at magnitude 1.17. Smaller numbers are brighter, and the faintest stars the eye can see are about 6.

How hot

About 8,600 K

That is the temperature of its surface, worked out from its colour, so it is a guide and not a measurement. It could be out by a few hundred degrees. The Sun's is 5,772 K. Hotter stars are bluer and cooler stars are redder, the same way a poker in a fire goes from red to white.

FomalhautThe Sun

In your sky now

Working it out…

Its names

Its own name: Fomalhaut
By constellation (Bayer): Alpha Piscis Austrini
Hipparcos catalogue: HIP 113368
Henry Draper catalogue: HD 216956
Spectral type: A3V

Where this comes from

Distance, brightness, colour and spectral type are from the HYG star database, version 4.4, by David Nash, shared under a Creative Commons Attribution-ShareAlike 4.0 licence. Its distances are those measured by the Hipparcos satellite. The temperature is worked out here from the colour with the formula of Ballesteros (2012), and the words are written for this site.