Using data from NASA’s Asteroid Terrestrial-Impact Last Alert System (ATLAS) survey, astronomers have detected a comet in the main asteroid belt, a place that is unusual for comets to be at. Named asteroid (248370) 2005 QN137, the solar system body was earlier identified as the eighth main-belt asteroid and discovered in 2005. But on July 7 this year, astronomers were surprised to find that the space rock had grown a tail, a property exhibited by comets.

Unlike asteroids, which mostly live in the main asteroid belt orbiting around the sun between orbits of Mars and Jupiter, comets mainly live in the Kuiper belt, an orbit that exists past the Neptune — the outermost planet in our solar system — and is 20 times wider than the main asteroid belt.

Comets are much smaller space rocks than asteroids and because of their small masses, they follow long elliptical orbits occasionally going very close to the sun. After living in the cold depths of the outer solar system for hundreds and thousands of years, they enter the inner solar system and as they approach the Sun, their surface evaporates leaving a dust trail and giving them their characteristic look.