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The neighborhood around a star can be dangerous. Comets, asteroids, and even planets can slam together. That can rip them apart and create massive clouds of dust and rock. And those clouds can be deceiving.

Consider Fomalhaut, the brightest star of the southern fish. It’s low in the southeast at nightfall and scoots across the south during the night. It’s the only bright star in that region of the sky, so it’s easy to pick out.

Fomalhaut is bigger, brighter, and heavier than the Sun — and billions of years younger. And it’s encircled by disks and rings of dust.

In 2008, pictures of the system from Hubble Space Telescope revealed a bright, compact object near one of those rings. For a long time, scientists thought it was a giant planet. They even gave it a name: Dagon. But a few years later, that pinpoint of light began to spread out. And before long, it vanished.

Continued study of the system suggested the object is really a cloud of dust that’s spreading out and growing fainter. It may be the debris from a collision between two “planetesimals” — big balls of rock and ice that are the building blocks of planets. It could also be the remains of a single planetesimal that passed too close to a giant planet and was ripped apart by the planet’s gravity. So Fomalhaut could have a planet — and perhaps several planets. But so far, we can’t see them.

Tomorrow: lyrical names for Fomalhaut and many other stars.

Script by Damond Benningfield

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