A sequence of Hubble Space Telescope images traces the orbital path of Fomalhaut b (inset), a giant planet orbiting the bright star Fomalhaut. The planet orbits on the inner edge of a massive band of dust that encircles the star (bright ring in the main photo; Fomalhaut itself is blacked out). Discrepancies in the planet's appearance suggest it may be encircled by large, bright rings or a massive cloud of dust. Astronomers are continuing to observe the system to try to solve the mystery of the planet's odd appearance. [NASA/ESA]
As seen from Earth, the star Fomalhaut is pretty lonely. You can see it this evening low in the southern sky — the only bright star in that part of the sky.
In reality, though, Fomalhaut isn’t alone. A large planet orbits the star — although it’s a world of mystery.
The planet was discovered a few years ago in pictures from Hubble Space Telescope. It’s between Fomalhaut and a giant ring of dust and ice that encircles the star. Its brightness suggested that the planet must be big and heavy.
When other astronomers looked for the planet with another space telescope, though, they couldn’t see it. These observations looked for infrared energy — the heat from the planet itself. The lack of an infrared detection convinced some that the planet didn’t exist. In fact, one team suggested that there were two small planets — one just inside the ring, and another just outside the ring.
But over the last year or so, other teams have confirmed the original discovery, although they suggest that the planet is smaller than originally thought. It may be surrounded by giant rings or a big cloud of dust, making it appear unusually bright at visible wavelengths.
If its orbit is aligned with the giant ring, the planet could be in for some trouble. In a couple of decades, it could plow into the ring, where it could be pounded by big space rocks. Some of those collisions might be visible to telescopes on Earth — in both visible and infrared light.
Script by Damond Benningfield, Copyright 2013
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