A humungous Earth-like planet found by US astronomers has changed the perception of planet formation. A rocky world found by Kepler space observatory should by rights have become a giant ball of gas, but has remained a planet for billions of years.
The newly discovered Kepler-10c planet has been dubbed â€˜Mega-Earthâ€™ thanks to its diameter of 29,000 kilometers and an estimated weight 17 times greater than Earth, which has a diameter of 12,742 kilometers. This makes Kepler-10c the biggest rocky planet ever discovered.
The new planet is circling a very old Sun-like star, Kepler-10, some 560 light years from Earth. If you look up in the sky this star can be seen in the Draco constellation, which is 300 million light years away.
The Kepler-10c planet is so unique because scientists hitherto believed that planets so big could only be made mostly of gas, like our solar systemâ€™s Jupiter and Saturn, which have a solid core of rock and metals, surrounded by a deep layer of frozen and liquid hydrogen, helium and other gases.
“A mega-Earth is a lot of solids concentrated in the same place without any gas. That is a problem because our understanding for how planets form requires the solids to get together in an environment where almost 99 percent of the mass … is hydrogen and helium,” Dimitar Sasselov, professor of astronomy at Harvard University and director of the Harvard Origins of Life Initiative, told reporters. Sasselov described the newly-found planet as â€œthe Godzilla of Earths.â€