Astronomers identify 8 new planets in Goldilocks zone

BOSTON, Jan. 6 (UPI) -- Astronomers have found eight new planets in the Goldilocks zones of their respective stars. That's eight new exoplanets that are potentially habitable.

The Goldilocks zone is the distance from a host star where temperatures would allow for water to exist in a liquid state -- not so close that the star's heat would boil it away, and not so far that all water would freeze.

"Most of these planets have a good chance of being rocky, like Earth," explained Guillermo Torres, a researcher at the Harvard-Smithsonian Center for Astrophysics and lead author of a new study on the discovery.

The eight new exoplanets double the total number of Earth-like alien worlds now confirmed to exist in the habitable zone. The research is years in the making. While Kepler has been able to spot new planets with increasing frequency, followup research to verify their size and orbital distance is time-consuming and difficult.

Of the eight new exoplanets, the two most like Earth are Kepler-438b and Kepler-442b, each of which orbit small red dwarf stars that burn much cooler than the sun. While Kepler-438b orbits its host star just every 35 days, it takes Kepler-442b 112 days to complete an orbit.

"We don't know for sure whether any of the planets in our sample are truly habitable," said co-author David Kipping. "All we can say is that they're promising candidates."

The new study is scheduled to be published in The Astrophysical Journal.