Discovery of New Type of Exoplanet: The Godzilla of Earths
A team of CfA astronomers, lead by Xavier Dumusque, recently discovered that Kepler-10C— a massive planet located in the Draco constellation 560 light years from Earth— has a solid core and a rocky surface, just like Earth. This discovery was announced at today's American Astronomical Society's meeting in Boston.
But knowledge of the exoplanet's existence is actually not news. It was discovered by NASA's Kepler Space Telescope in 2011, but, due to it's enormous size, it had been automatically assumed to be a smaller version of Neptune with a layer of gas surrounding it, rather than a rocky, earth-like planet. Until today, astronomers didn't think that a rocky Kepler-10 C-sized planet could exist. They thought that the large diameter of the planet would most likely be due to a gradual accumulation of hydrogen over time.
Dumusque explains that in fact, "Kepler-10 C didn't lose its atmosphere over time. It's massive enough to have held onto one if it ever had it [...] It must have formed the way we see it now."
The CfA believes that the Kepler-10 C system is probably very old, possibly born less than 3 billion years after the Big Bang. The CfA also believes that "the system's early formation suggests that, although the materials were scarce, there were enough heavy elements like silicon and iron to form rocky worlds relatively early on in the history of the universe."
The implications of this discovery are huge. According to Dimitar Sasselove, a CfA researcher, "Finding Kepler-10 C tells us that rocky planets could form much earlier than we thought [...] And if you can make rocks, you can make life."
This finding reinforces the notion that particularly ancient stars could be hosts to rocky Earths, which provides astronomers with many more planets to explore when searching for intelligent extraterrestrial life. Where previously they had mostly ruled the planets of old stars out, now they may give them a closer look.