Nasa has announced the discovery of 219 new suspected planets outside our solar system.

The figure includes 10 that are ‘rocky’ like Earth and orbiting the habitable zone of a star. known as the ‘Goldilocks zone’; neither too close to their star, and therefore too hot, nor too far away and too cold for liquid water to exist.

The presence of water is seen as a key factor for the existence of life.

The discoveries by the Kepler telescope do not mean that the planets have life, just that the basic requirements for life have been met.

NASA say this is the most “comprehensive and detailed catalog” of candidate exoplanets – which are planets outside our solar system – in Kepler’s first four years of data.

This new discovery brings to 4,034 planet candidates identified by Kepler.

Data also suggests two distinct size groupings of small planets. The team found a clean division in the sizes of rocky, Earth-size planets and gaseous planets smaller than Neptune.

The findings were presented at a news conference Monday at NASA’s Ames Research Center in California’s Silicon Valley.

“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogs – planets with roughly the same size and orbit as Earth,” said Mario Perez, Kepler program scientist in the Astrophysics Division of NASA’s Science Mission Directorate.

Adding, “understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”

The Kepler space telescope hunts for planets by detecting the minuscule drop in a star’s brightness that occurs when a planet crosses in front of it, called a transit.

This is the eighth release of the Kepler candidate catalog, gathered by reprocessing the entire set of data from Kepler’s observations during the first four years of its primary mission.