US astronomers discover planet twice as large as earth

Mega EarthWashington (ISJ) ? US astronomers have discovered a rocky planet more than twice the size of earth. Kepler-10c, as the planet has been named, weighs 17 times as much as Earth and its existence was not known until now.


"We were very surprised when we realized what we had found," said astronomer Xavier Dumusque of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, who led the analysis using data originally collected by NASA's Kepler space telescope.


Kepler-10c orbits a sun-like star every 45 days, making it too hot to sustain life. It is located about 560 light-years from Earth in the constellation Draco. The system also hosts Kepler-10b, the first rocky planet discovered in the Kepler data.


It was originally spotted by NASA's Kepler spacecraft. The new planet is known to have a diameter of about 18,000 miles, 2.3 times as large as Earth. It fell in the category of planets known as mini-Neptunes, which have thick, gaseous envelopes.


"Kepler-10c didn't lose its atmosphere over time. It's massive enough to have held onto one if it ever had it," explains Dumusque. "It must have formed the way we see it now."


Planet formation theories have a difficult time explaining how such a large, rocky world could develop. However, a new observational study suggests that it is not alone.


The discovery that Kepler-10c is a mega-Earth also has profound implications for the history of the universe and the possibility of life. The Kepler-10 system is about 11 billion years old, which means it formed less than 3 billion years after the Big Bang.


The early universe contained only hydrogen and helium. Heavier elements needed to make rocky planets, like silicon and iron, had to be created in the first generations of stars. When those stars exploded, they scattered these crucial ingredients through space, which then could be incorporated into later generations of stars and planets.


This process should have taken billions of years. However, Kepler-10c shows that the universe was able to form such huge rocks even during the time when heavy elements were scarce.


This research implies that astronomers shouldn't rule out old stars when they search for Earth-like planets. And if old stars can host rocky Earths too, then we have a better chance of locating potentially habitable worlds in our cosmic neighbourhood.

Sources: NASA and Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts press releases/Pix Credit: HSCA


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