A space telescope from NASA has found 219 new planet candidates, 10 of which are near-Earth size and orbiting the habitable zone of a star.

This zone is the range of distance from a star, where liquid water could form on the surface.

The findings 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 illustration depicts a sample of the many planets discovered by NASA's Kepler space telescope | Image: NASA/Wendy Stenzel

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.

Image: NASA Ames/N. Batalha and W. Stenzel

The findings were presented at a news conference at NASA's Ames Research Centre in California's Silicon Valley.

Mario Perez is a Kepler program scientist with NASA: "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.

"Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth."

"Are we alone? Maybe Kepler today has told us indirectly, although we need confirmation, that we are probably not alone."

The Kepler space telescope is hunting for planets by detecting the minuscule drop in a star's brightness, which happens when a planet crosses in front of it.

But NASA say of roughly 50 near-Earth size habitable zone candidate planets found, just over 30 have been verified so far.