Earthlike planet found, but extremely hot
Kepler 78b, a planet some 400 light-years away, is like hell on earth.
Astronomers described it as the first Earth-size planet that seems to be made of the same mixture of rock and iron as Earth, and that orbits a star similar to our sun.
But Kepler 78b would not be a pleasant place to visit. It whirls around its parent star, Kepler 78, at a distance of less than a million miles, and its year — the time it takes to complete one orbit — is just eight and a half hours.
At that close proximity, the surface of Kepler 78b is infernally hot: 3,500 to 5,000 degrees Fahrenheit.
Viewed from the surface of Kepler 78b, its star would cover 80 times more of the sky than the sun does in Earth’s sky.
Kepler 78b is one of more than 150 planets spotted by NASA’s Kepler spacecraft, which noted the dimming of the starlight when a planet passed in front.
An assumption is that it was originally a gas giant like Saturn and that as the planet spiraled in toward the star, all of the gases were stripped away, leaving just the rocky core at the center.