Astronomers have for the first time discovered a planet that is similar in mass to the Earth and moves in front of its star during every orbit. Although the planet has about the same mass as the earth, the diameter is about sixty percent larger. This suggests that the planet is rich in gases.
"Although this planet may have the same mass as the earth, the planet is certainly not earthy," notes researcher David Kipping. "It proves that there is no clear dividing line between rocky worlds such as the earth and water worlds or gas giants."
The planet - which bears the name KOI-314c - has a density that is only thirty percent greater than the density of water. It suggests that the planet is surrounded by a hundreds of kilometers thick atmosphere consisting of hydrogen and helium. Perhaps the planet began its life as a mini Neptune and over time it lost a large proportion of the gases in its atmosphere through evaporation. The planet is pretty close to its star. It is therefore too hot for life.
The two of you
KOI-314c circles around a red dwarf that is about 200 light-years away. It takes the planet 23 days to complete a circle around the star. And the planet is not alone: another planet circles around the star. This is about the same size as KOI-314c, but has a much higher density and weighs four times more than our earth. This planet needs thirteen days to complete a circle around the star.
It is partly thanks to this second planet that researchers were able to estimate the mass of KOI-314c so well. The two planets pull together and therefore the time it takes to complete a circle around their star varies slightly. By studying time and again how much time the planets needed for a circle around their star, the researchers could finally determine the mass of both planets.