U.S. space agency NASA announced the discovery of more than 200 new planets on Monday, 10 of which are believed to be about the right size and temperature to support life. Of the 219 new suspected planets to have been discovered by NASA's Kepler telescope, 10 were found to exist in the so-called 'Goldilocks zone' of their solar system. This refers to the distance between the planet and their star, which is neither too hot nor too cold to support complex life. The presence of liquid water on these "rocky" Earth-like planets is seen as a key ingredient required for the existence of life. "Are we alone? Maybe Kepler today has told us indirectly, although we need confirmation, that we are probably not alone," Mario Perez, Kepler program scientist, said at a news conference. NASA launched the Kepler telescope in 2009 in a bid to discover whether other Earth-like planets are common or rare. The latest identification of suspected exoplanets – planets outside our own solar system – brings the tally discovered by the Kepler telescope to 4,034. The number of worlds thought to be approximately the same size and temperature as Earth is around 50.