SAN JOSE, Calif. — One of the most common kinds of planets detected by NASA's Kepler telescope appears to be a type that doesn't exist in our own solar system, a leading astronomer on the Kepler team said Friday.
This type of planet has a size in the range between two and four times Earth's diameter, but it shouldn't be called a "super-Earth" or a "mini-Neptune," said Berkeley astronomer Geoff Marcy, one of the world's most experienced planet-hunters. For now, he's calling them "sub-Neptunes."
Based on an analysis of the Kepler planets' sizes and densities, sub-Neptunes should have a rocky core that's swathed in a thick layer of hydrogen and helium gas. That combination distinguishes them from rocky planets like Earth, as well as gas giants like Jupiter and ice giants like Neptune.
"They dominate the planet census, and yet none of them are found in the solar system," Marcy said here during a symposium at the annual meeting of the American Association for the Advancement of Science.
... "Thought you might enjoy hearing, watching & reading about this recent scientific discovery. It is yet another in a series of deep space discoveries that indicates the existence of solar systems with planets likely with attributes very similar to planet Earth: "...