Signs of first planet found outside our galaxy

Astronomers have found hints of what could be the first planet ever to be discovered outside our galaxy. Nearly 5,000 "exoplanets" - worlds orbiting stars beyond our Sun - have been found so far, but all of these have been located within the Milky Way galaxy. The possible planet signal discovered by Nasa's Chandra X-Ray Telescope is in the Messier 51 galaxy. This is located some 28 million light-years away from the Milky Way. This new result is based on transits, where the passage of a planet in front of a star blocks some of the star's light and yields a characteristic dip in brightness that can be detected by telescopes.