the 17th star (excluding the Sun) in order of apparent brightness. It is used in navigation because of its conspicuous place in a sky region otherwise lacking in bright stars. It lies in the southern constellation Piscis Austrinus, 25 light-years (light-year) from Earth. A white star, it has an apparent magnitude of 1.16. A sixth-magnitude companion star, HR 8721, is yellow and orbits at a distance of about 0.9 light-year. A belt of dust orbits between 19.9 and 23.6 billion km (12.4 and 14.7 billion miles) from the star. Images taken with the Hubble Space Telescope in 2004 and 2006 showed a planet, Fomalhaut b, orbiting inside the dust belt at a distance of 17.8 billion km (11.1 billion miles) from the star. These were the first confirmed images of an extrasolar planet. The planet has a mass three times that of Jupiter and an orbital period of 872 years.