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

The figure includes 10 that are “rocky” like Earth and which exist in their solar system's '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.

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In a tweet, Nasa said: "Scientists using @NASAKepler have identified 219 potential new worlds!"

The discoveries bring the total number of suspected exoplanets – planets outside our solar system – found by the Kepler space telescope to more than 4,000.

"This carefully measured catalogue is the foundation for directly answering one of astronomy’s most compelling questions – how many planets like our Earth are in the galaxy?” said Susan Thompson, a research scientist at the SETI Institute, which searches for signs of extra-terrestrial life.

And, in a statement, Nasa said: “There are now 4,034 planet candidates identified by Kepler. Of which, 2,335 have been verified as exoplanets. Of roughly 50 near-Earth size habitable zone candidates detected by Kepler, more than 30 have been verified.

Nasa finds flowing water on Mars - in pictures Show all 7 1 /7 Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures The MAVEN spacecraft orbiting Mars EPA Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures Nasa finds flowing water on Mars - in pictures In this handout illustration provided by NASA/JPL, an artist's conception of the Phoenix Mars Lander on the Red Planet. Phoenix is slated to land on Mars on May 25, 2008.

“Additionally, results using Kepler data suggest two distinct size groupings of small planets. Both results have significant implications for the search for life.”

Mario Perez, a Kepler programme scientist at Nasa, stressed the importance of the space telescope.

“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogues – planets with roughly the same size and orbit as Earth,” he said.

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