Will extraterrestrial life be found soon?
By Raif Karerat
WASHINGTON, DC: NASA scientist Natalie Batalha recently stated that the galaxy is inhabited by billions of Earth-like planets, all of which are the approximate size of the Earth, all rocky, and all orbiting medium-sized, yellow stars.
It was just yesterday that NASA’s Kepler Space Telescope discovered its namesake, Kepler-452b, a planet NASA describes as the “closest twin to Earth” found to date.
During NASA’s press conference Thursday, a Washington Post reporter asked whether the latest Kepler data offered any insight into how many Earth-like planets were orbiting sun-like stars, and Batalha, an astrophysicist who is the mission scientist for the Kepler telescope, emailed her answer:
Previous estimates of eta-Earth suggest that 15-25% 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. So how does that translate to the number of planets in the galaxy? M, K, and G dwarfs comprise about 90% of the stars in the galaxy. Conservatively speaking, if 15% of stars have a planet between 1 and 1.6 times the size of Earth in the Habitable Zone, then you’d expect 15% of 90% of 100 billion stars to have such planets. That’s 14 billion potentially habitable worlds.
Kepler was launched in 2009 and specifically designed to hunt for planets around distant stars. According to CBC, it searches for a dip in the light from a star as the planet passes in front of it, blocking part of the cosmic luminescence. To date, it has found more than 3,000 planet candidates and confirmed more than 1,000 planets.