Astronomers have confirmed the existence of an Earth-like planet in the "habitable zone" around a star not unlike our own. The planet, Kepler 22-b, lies about600 light-years away and is about 2.4 times the size of Earth, and has a temperature of about 22C. It is the closest confirmed planet yet to one like ours - an "Earth 2.0". However, the team does not yet know if Kepler 22-b is made mostly of rock, gas or liquid. During the conference at which the result was announced, the Kepler team said that it had spotted some 1,094 new candidate planets. The Kepler space telescope was designed to look at a fixed swathe of the night sky, staring intently at about 150,000 stars. The telescope is sensitive enough to see when a planet passes in front of its host star, dimming the star's light by a minuscule amount. Kepler identifies these slight changes in starlight as candidate planets, which are then confirmed by further observations by Kepler and other telescopes in orbit and on Earth.