Astronomers have discovered thousands of likely planets in other stars systems. Yet they’ve actually seen only a handful of those worlds. One of those may orbit Fomalhaut, a bright white star that arcs low across the south on autumn nights. Most planets are discovered indirectly — through their gravitational tug on a parent star, for example, or when a planet passes in front of the star and blocks a tiny bit of the star’s light. The possible planet orbiting Fomalhaut is an exception. It was discovered in a series of pictures snapped by Hubble Space Telescope. Astronomers were using Hubble to view a giant disk of dust that surrounds Fomalhaut. There are wide gaps in the disk that could have been swept clear by a large planet. The Hubble images showed a bright dot within the disk. As Hubble took more pictures over the years, the dot moved in a way that was consistent with a planet orbiting the star. If it is a planet, it’s probably about three times the mass of Jupiter, the giant of our
