Nasa announcement: What we know about the space agency's mysterious, major breakthrough

Nasa is preparing for a huge announcement from its planet-hunting telescope. It has said only that it will brief the press on Thursday and that the discovery has been made by the Kepler space telescope. It also said that Google has been involved in the breakthrough discovery. But beyond that it said very little. Still, some clues give us a little insight into what the major announcement might be about to actually reveal. The craft was launched into space in 2009, and has been looking for exoplanets ever since.