A NASA spacecraft just spotted a giant hole creeping over the surface of the sun. It sounds like the recipe for a doomsday blockbuster - the sun slowly gets consumed by blackness, throwing our planet into a cold, dark frenzy. But actually, this hole is no cause for alarm. It's called a coronal hole, an astronomical phenomenon that pops up on the sun's corona from time to time.
According to NASA, these holes mark low-density spots where the sun's magnetic field opens freely into interplanetary space, allowing hot material from the corona to speed outward.