Exoplanets are planets orbiting other stars. It's widely claimed that the official definition of "planet" excludes exoplanets. There are two problems with this: It's wrong, and it's impossible to define "planet" anyway.
We've seen a lot of incredible planet discoveries over the years, but this one's definitely among the coolest. It's a planet roughly the size of Neptune, but what makes it unique is the number of suns nearby, so many that the gravitational pull should destroy it.