NASA’s primary planet searcher, the Kepler space observatory, produced one its most important findings the other day with the discovery of a world just 1.4 times the size and 4.6 times the mass of Earth – the smallest planet ever discovered outside of the solar system.
Launched in March 2009, the Kepler Mission was designed to search for Earth-like planets. While most planets observed to date have been several times larger and composed mostly of gas, this newly discovered planet – dubbed Kepler 10b – is made of a rock with a similar density to iron, suitable for a human to stand on. That is, if the surface temperature didn’t reach above 1,300 °C.
So, why is it significant if we couldn’t even live on it?
While the discovery of a rocky planet outside of the solar system may have been predictable, the fact that one had not been found still led to some difficulties when debating whether other habitable Earth-like planets existed. With astronomers now safely in the knowledge that they can find these rocky planets, the search for more can begin.
“Although this planet is not in the habitable zone, the exciting find showcases the kinds of discoveries made possible by the mission and the promise of many more to come,” said Douglas Hudgins, a Kepler program scientist at NASA.
The discovery (although slightly disputed) of Gliese 581g last year and now the emergence of Kepler 10b means that planets have been discovered separately in the habitable zone (goldilocks zone) of a star and with a similar composition to that of Earth. Now, if we could find a planet that combined the two, things would start to get really interesting…