Fomalhaut

It’s not easy to take a picture of a planet orbiting another star. A planet is much smaller than a star, and it’s so faint that it’s drowned out by the star’s brilliant light. A decade ago, though, Hubble Space Telescope managed to snap the first picture of an exoplanet. It orbits Fomalhaut, the autumn star.

Fomalhaut is about 25 light-years away. It’s twice as big and heavy as the Sun, and about 16 times brighter. And it’s only one-tenth of the Sun’s age — about 450 million years.

It’s surrounded by a wide disk of dust. The disk is divided into several bands, with gaps between them. The inner band comes within a few million miles of Fomalhaut. The outer band extends almost 20 billion miles away from it.

Hubble found the planet in the outer regions of the disk. That distance was one reason Hubble could see the planet — it’s well away from Fomalhaut’s glare. Even so, it appears as no more than a tiny dot of light.

A few years ago, the planet was given a formal name: Dagon, for a Semitic god. Dagon probably is a giant, similar to Jupiter, the biggest planet of our own solar system. And there are hints that at least one more planet lurks inside Fomalhaut’s disk — perhaps waiting to have its own picture taken.

Fomalhaut is low in the southeast as night falls. It stays low in the sky as it arcs across the south during the night. It’s the only bright star in that region of the sky, though, so it’s easy to pick out.

Script by Damond Benningfield