This latest discovery marks a milestone that takes scientists one step closer to finding a planet like our own.
NASA’s Kepler mission has found the first Earth-size planets orbiting a sun-like star outside our solar system. However they’re too hot to support liquid water — or life.
Two weeks ago, Kepler found a planet that was the perfect temperature. But this planet, Kepler-22b, is too big to have a rocky surface.
The new discoveries, Kepler-20e and Kepler-20f, are the right size. But they’re close to their star, making them fiery hot worlds.Kepler-20e and 20f are rocky places, made of silica and iron — Earthlike, but without an atmosphere.
The new planets reside within a curious five-planet solar system. It’s unlike our solar system, where small, rocky worlds circle close to the sun and large, gaseous worlds are farther away.Instead, the planets that circle star Kepler-20 are organized in alternating sizes: large, small, large, small and large.
The surface temperature of Kepler-20e, which orbits its sun every 6 days, is more than 1,400 degrees Fahrenheit — hot enough to melt glass. Kepler-20f orbits every 19.6 days and is 800 degrees — as hot as Mercury.
Researchers can’t rule out the possibility that the planets had liquid water after their creation, when they might have been farther from the sun. Perhaps there was a window of time — several billion years long — when they were habitable.
