KIC 8462852 is a star somewhat more massive, hotter, and brighter than the Sun. It’s about 1,500 light-years away, a decent distance, so it’s too faint to see with the naked eye. The Kepler data for the star are pretty bizarre: There are dips in the light, but they aren’t periodic. They can be very deep; one dropped the amount of starlight by 15 percent, and another by a whopping 22 percent!
Straight away, we know we’re not dealing with a planet here. Even a Jupiter-sized planet only blocks roughly 1 percent of this kind of star’s light, and that’s about as big as a planet gets. It can’t be due to a star, either; we’d see it if it were. And the lack of a regular, repeating signal belies both of these as well. Whatever is blocking the star is big, though, up to half the width of the star itself!