Scorching hot Earth-like
planet found

Kepler 78b is the smallest exoplanet whose mass and size are known. It is just 1.2 times bigger than Earth, 1.7 times more massive, and has an almost identical density.

Scientists believe that, like the Earth, Kepler 78b mostly consists of rock and iron. There the similarities end, however. The planet hugs its parent star so closely that nothing could live on its scorching surface.

Kepler 78b’s year is just 8.5 hours long – the length of time it takes to complete one orbit round its star.

“It’s Earth-like in the sense that it’s about the same size and mass, but of course it’s extremely unlike the Earth in that it’s at least 2,000 degrees hotter,” said Dr Josh Winn, from the Massachusetts Institute of Technology, US, who took part in the research published in the journal Nature.

“It’s a step along the way of studying truly Earth-like planets.”

American and European teams of astronomers examined data from observatories in Hawaii and the Canary Islands.

A handful of exoplanets the size or mass of the Earth have been discovered, but Kepler 78b is the first for which both values have been measured.