Mystery of Missing Exoplanet May Be Solved

Anyone seen Fomalhaut b? In 2008 we learned the exoplanet had been spotted in groundbreaking fashion by the Hubble Telescope, but nobody's caught a glimpse of it for quite a while. Now astronomers think they know why. Turns out, Fomalhaut b may not have been an exoplanet at all, but rather a cloud of dust caused by the collision of two big asteroids, reports USA Today. And now that dust seems to have finally dissipated in deep space, say researchers out of the University of Arizona. The story takes some unpacking: Exoplanets, or planets outside our solar system, aren't exactly rare, with the count now at more than 4,100, per the New York Times. The vast majority have been discovered indirectly, based on telltale "stellar wobbles and shadows," explain the researchers. Not so with Fomalhaut b.

More than a decade ago, astronomers poring over Hubble images detected what appeared to be an exoplanet orbiting the star Fomalhaut. The discovery was big news because the newly christened Fomalhaut b was one of the first exoplanets to be directly observed—by the Hubble telescope. In 2014, however, a University of Arizona astronomer discovered that the exoplanet seemed to have vanished, which would be exceedingly weird behavior for an exoplanet. The new study in PNAS lays out the theory that the exoplanet never existed in the first place. "I'll buy it, if I can get a three-year return policy," says astronomer Paul Kalas of the University of California, Berkeley, who was not involved with the study and was one of the scientists who first discovered Fomalhaut b. More data will need to be collected to confirm. (More discoveries stories.)