After discovering Earth's "bigger, older cousin" amid several exoplanets recently spotted by the Kepler Telescope, NASA noted there could be a billion other "Earths" within our own Milky Way Galaxy.
According to the Washington Post, NASA scientist Natalie Batalha said that means there are likely one billion planets in our immediate galactic neighborhood where humans could theoretically live.
"Previous estimates of eta-Earth suggest that 15-25 percent of stars host potentially habitable planets. These estimates are based largely on discoveries of planets orbiting the cooler stars called M dwarfs. These new discoveries suggest that the statistics for sun-like stars are roughly in-line with estimates from the cooler M-type stars," told the Post. "So how does that translate to the number of planets in the galaxy? M, K, and G dwarfs comprise about 90 percent of the stars in the galaxy. Conservatively speaking, if 15 percent of stars have a planet between 1 and 1.6 times the size of Earth in the Habitable Zone, then you'd expect 15 percent of 90 percent of 100 billion stars to have such planets. That's 14 billion potentially habitable worlds."
Despite NASA's statement that Kepler-452b could be a "cousin" to Earth, the space agency actually knows very little about it. All they know for sure is it is similar in size and distance from its host star, which also shares similarities to the sun.
NASA's only view of the planet has come from the Kepler Telescope, so its composition and atmosphere is widely unclear.
"We've been able to fully automate our process of identifying planet candidates, which means we can finally assess every transit signal in the entire Kepler dataset quickly and uniformly," Jeff Coughlin, Kepler scientist at the Search for Extra Terrestrial Intelligence Institute in Mountain View, Calif., said in a press release. "This gives astronomers a statistically sound population of planet candidates to accurately determine the number of small, possibly rocky planets like Earth in our Milky Way galaxy."
