Five potential Earth twins with conditions capable of supporting life have been discovered orbiting Sun-like stars.
Other planet candidates identified by American space agency Nasa's new Kepler space telescope could have life-bearing moons.
Astronomers also confirmed the existence of a six-planet solar system centred on a Sun-like star named Kepler-11.
The wealth of observation data has amazed scientists and greatly boosted the chances of life evolving beyond the Earth.
Nasa administrator and former astronaut Charles Boden said: "In one generation we have gone from extraterrestrial planets being a mainstay of science fiction to the present, where Kepler has helped turn science fiction into today's reality."
The latest batch of Kepler data identified what are believed to be several hundred new planets orbiting distant stars.
Of these, 54 sit within the habitable or "Goldilocks zone" - the region just the right distance from the parent star to allow conditions that are not too hot and not too cold for liquid surface water and life to exist.
Five of the candidate planets, yet to be verified by follow-up observations, are near-Earth sized. They are likely to be small, rocky planets with atmospheres and possibly oceans and rivers of flowing water, and any or all of them could be places where primitive or advanced life exists.
The remaining 49 habitable-zone candidates range from "super-Earth" worlds up to twice the size of Earth to planets bigger than Jupiter.
Findings from Kepler-11 appear in the latest issue of the journal Nature.