Kepler-22b was thought to have a temperature similar to that of Earth, according to modeling by Borucki and colleagues.

CNN: 3 new planets could host life

William Borucki, the driving force behind and principal investigator on the Kepler mission, said he was "delighted" by the fresh batch of results.

BBC: Kepler telescope: Earth-sized planets 'number 17bn'

"Another four years would have been frosting on the cake, but we have a nice cake now, " said William Borucki, the project's principal scientist.

CNN: Planet-hunting Kepler spacecraft in trouble

Borucki said the new planets are "by far" better candidates for life than any others we know about, but a handful of others also have been identified as potentially capable of hosting life.

CNN: 3 new planets could host life

And because what we're finding - planets that are bigger than Jupiter or smaller than Mercury, denser than iron or lighter than styrofoam - Bill Borucki, the Kepler Mission's principal investigator, believes the next ten or 15 years is going to be even more exciting than the last.

BBC: From counting to characterising exoplanets