In 2008, astronomers snapped what they claimed was the first actual picture of an exoplanet. The Hubble Space Telescope image showed a pinpoint of light orbiting a star called Fomalhaut approximately 25 light-years from Earth.
Now, a different team of scientists spying on the presumed planet, dubbed Fomalhaut b, with the Spitzer Space Telescope suggests that the bright dot in the original image isn’t a planet at all. Though the team isn’t sure what the dot is, the point of light doesn’t appear to radiate at the infrared wavelengths where exoplanets should, a team led by Markus Janson of Princeton University reports in a paper posted online January 24 at arXiv.org.
This isn’t the first time that Fomalhaut b has stumped astronomers. Ground-based infrared telescopes haven’t been able to see it, and it’s tracing an unexpected path around its star. Theories proposed to explain the imaged “planet” range from a background star to light scattered by a dust cloud.
But these results don’t mean that Fomalhaut is a lonely star: It’s circled by a dusty debris disk that bears an elliptical shape resembling the handiwork of a giant planetary shepherd — a planet that just hasn’t been found yet. “The ‘real’ Fomalhaut b still hides in the system,” the scientists conclude.