The dotted white streak cutting across this photo of a faraway galaxy might seem like a nuisance for astronomers, but it's actually the mark of a previously undiscovered asteroid.
The image, snapped by the Hubble Space Telescope from its decades-long perch in low Earth orbit, is one of many that have been photobombed by asteroids whizzing in front of the telescope's eyes. A large group of citizen scientists poring over such old Hubble photos has discovered more than 1,000 previously unknown space rocks that reside in the main asteroid belt between Mars and Jupiter, hundreds of them less than 0.6 miles (1 kilometer) wide, NASA announced on Thursday (April 18).
