The so-called “mega-Earth” circles a very old star called Kepler-10, which is located about 560 light-years away from Earth in the constellation Draco.
Physicist Dimitar Sasselov, the Director of the Harvard Origins of Life Initiative, said the discovery, announced at the American Astronomical Society meeting in Boston, U.S., was a surprise since big planets were believed to be mostly gas, not solid rocky bodies like Earth or Mars.
Sasselov told reporters at a news conference in Boston, U.S. that the scientists do not yet understand how the planet, known as Kepler-10c, formed, with a diameter of about 18,000 miles (29,000 km), 2.3 times greater than Earth’s.
“A mega-Earth is a lot of solids concentrated in the same place without any gas. That is a problem because our understanding of how planets form requires the solids to get together in an environment where almost 99 per cent of the mass is hydrogen and helium,’’ he added.
He added that large planets should gather up massive amounts of gas in the process – or so scientists thought.
“However the mega-Earths are formed, the discovery of another type of rocky world augurs well in the search for life beyond Earth,’’ Sasselov added.
In the solar system, there is nothing between the size of Earth, the largest rocky planet, and Neptune, the smallest gas giant with a diameter nearly four times Earth’s.
“We really want to know about these planets,” astronomer Lars Buchhave, with the Harvard-Smithsonian Centre for Astrophysics, told reporters. (Reuters/NAN)