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October 7, 2017

Every star in the night sky looks like nothing more than a dot against the darkness of space. Some are brighter than others, and some show a bit of color, but they’re all still just pinpoints of light. As modern telescopes allow us to zoom in more closely, though, we see that there’s a lot more to a star system than meets the eye.

An example is Fomalhaut, the leading light of Piscis Austrinus, the southern fish. It’s low in the southeast at nightfall, and at its highest, due south, a few hours later. It’s pretty bright, and there are no other bright stars around it, so it stands out.

Fomalhaut itself is bigger, heavier, and brighter than the Sun, and billions of years younger.

It’s surrounded by a disk of debris that spans tens of billions of miles. Much of it consists of grains of dust coated with ice that are warmed by Fomalhaut, causing the disk to glow in the infrared. But the disk also contains lots of icy comets and rocky asteroids. They stage frequent collisions, renewing the supply of material in the disk.

The disk also contains a giant planet. It’s been photographed by Hubble Space Telescope, although all we see is a small orange dot. The planet follows an elongated orbit around Fomalhaut. That may mean that another planet that’s closer to the star is pushing the visible planet around. That would give the system at least two planets, plus a vast cloud of debris — meaning there’s a lot more to Fomalhaut than meets the eye.


Script by Damond Benningfield


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