Artist’s concept of the Kepler Space Telescope against a background of planets and stars. Kepler discovered over 1,000 of the 4,000+ known exoplanets. Now, based on Kepler data, scientists estimate that 1 in 4 sunlike stars has at least 1 planet about the same size as Earth. Image via NASA/Ames Research Center/W. Stenzel/D. Rutter/Penn State News.
How many Earth-sized planets – orbiting in their star’s habitable zone, where liquid water could exist – are out there in our Milky Way galaxy? Scientists have been discovering exoplanets by the thousands in recent years, and now they have a better idea of what the answer to that question is. According to a new study from Penn State University based on data from the Kepler Space Telescope, it turns out that one in four sunlike stars should have at least one planet similar in size to Earth and orbiting in its star’s habitable zone.
The new peer-reviewed paper describing the results was published in The Astronomical Journal on August 14, 2019.
Clearly, this is an exciting study! It has direct implications for the possibility of life on other worlds. There are about 200 billion stars altogether in our galaxy, and about 10 percent ...