Two weeks ago Kepler gave us its first probable earth-like world orbiting the habitable zone of a sun-like star. This week it’s not one but two, count ‘em two, small and probably rocky worlds. And these guys are tiny by exoplanetary standards:
(AstronomyNow) — A rocky exoplanet smaller than Earth, and its neighbouring Earth-sized world with a thick water-vapour atmosphere, have been detected around a Sun-like star already known to host three larger planets.
The planets were detected by NASA’s Kepler spacecraft, which watches for tiny dips in brightness of thousands of stars as a planet transits in front of them, temporarily blocking out a miniscule fraction of their light. One of the new planets identified around 1,000 light year distant Kepler-20 – Kepler-20f – has a radius almost identical to Earth at 1.03 Earth radii, and the other is just 0.87 Earth radii – smaller also than planet Venus – and is the smallest exoplanet ever identified around a Sun-like star.