In the past quarter century, astronomers have found a smorgasbord of worlds beyond our own: icy exoplanets and fiery exoplanets, planets the size of the moon and planets bigger than Jupiter. Some have surfaces that resemble toffee; others are like cotton candy. This cosmic candy store now carries more than 4,000 worlds, and the inventory is only expanding. The pace of discovery is so fast that the numbers cited in this story will probably be out of date by next month.
That means the latest additions are not, on their own, noteworthy. The novelty lies, instead, in how they were found, and the process is anything but sweet. It’s downright gnarly: Astronomers recently detected six exoplanets by looking for signs that they’re being shredded to pieces by their stars.
It wasn’t long ago that astronomers had no proof that planets outside of our solar system even existed. Now they’re finding distant worlds in the midst of their slow demise.
The idea for this technique came to Carole Haswell, an astrophysicist at the Open University in the United Kingdom, about a decade ago. At the time, she was studying telescope data for a distant, sunlike star called WASP-12, located in the pentagon-shaped constellation of Auriga. But when Haswell analyzed the telescope data, the star seemed to be missing something pretty important: a chunk of starlight.
Haswell had expected to detect the kind of emission that stars like our sun are known to exhibit. “When we looked at WASP-12, at the wavelengths where you could expect to see that, we were seeing absolutely zero light,” she says. She suspected that the explanation lay not with the star itself, but with its companion, a planet about the size of Jupiter. The planet completes one loop around WASP-12 in a single Earth day. The telescope observations showed that the planet, scorched to temperatures hotter than some actual stars, was being torn apart.