What is Orbiting the Eye of Sauron?

Pictures from the Hubble Space Telescope introduced us to the star Fomalhaut, which is informally called the Eye of Sauron because that's what it looks like. More images led astronomers to believe there was a planet orbiting the star, but they weren't sure because it didn't show up on infrared and didn't appear to disturb the star's photogenic ring of dust. Now we know more.

The original astronomers realized it’s possible the planet was enshrouded in dust, which would absorb the planet’s intrinsic infrared light, but still reflect enough starlight from Fomalhaut to be visible to Hubble. If it were a gas giant with the mass of Saturn or so, it would be able to hold on to a cloud of dust and yet not be bright enough to see in the infrared. They also found with follow-up observations that the orbit of the object didn’t cross the ring, so the ring’s gravitational disruption wasn’t a problem.

So where do we stand now? Last year, more observations were taken, and were just released. They clearly show the blob has moved again, and the movement is consistent with the orbit of, well, something, including a planet. But the orbit is really weird: It’s highly elliptical, taking the planet (if that’s what it is) as close to the star as 7 billion kilometers, and as far out as 45 billion km. Mind you, that puts the inner part of its orbit farther out than Neptune orbits the Sun!

But the new images raise even more questions about the possible exoplanet. Read more about this mystery of deep space at Bad Astronomy.