Scientists announced on Monday that there may be several billion habitable exoplanets orbiting stars in the Milky way galaxy. The research team, made up of astronomers from U.C. Berkeley and the University of Hawaii, Manoa, based their findings on a statistical analysis of all observations of the NASA Kepler space telescope. About one in five stars that are like our sun have Earth-sized planets that have a surface temperature that would be conductive to life.
“When you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye. That is amazing,” said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler data.
The astronomers cautioned that just because a planet is in the habitable zone around a star doesn't mean that it is actually capable of supporting life. Some planets may have thick atmospheres making it to hot on the surface for life to survive. Last week the team announce discovery of an Earth-sized world that is mostly like made up of rock and iron like the Earth. Unfortunately it has a surface temperature of 2,000 degrees Kelvin which is far to hot to support life.
Although Kepler's scientific mission has ended due to a malfunctioning reaction wheel there are still many discoveries to be made from collected data. About a year's worth of data remain to be fully analyzed so there are likely several more discoveries yet to come.