NASA discovers ‘Mega-Earth’

05 June 2014
Posted by Chris Smith.

A massive planet twice the size and 17 times the mass of Earth has been announced by scientists at NASA.

Kepler-10c is a planet discovered by Kepler, a space telescope launched by NASA, as part of its mission to discover new worlds similar to Earth.

It is around twice the size of the Earth, but new research published this week in Arxiv has shown it is heavier than anyone thought possible.

Weighing in at around 17 times heavier than the earth, Kepler-10c is composed of dense, solid material.

Planets of this magnitude usually have such intense gravitational pulls that a cloud of gas develops around them during formation, causing them to reach great sizes.

This is common to all the giants in our own solar system, such as Neptune or Saturn. Kepler-10c weighs the same as Neptune, but is about half the diameter, but it does not have this same gassy envelope.

Previously it was unheard of for a planet of this size to be composed entirely of rocky material.

Kepler-10c is located over 500 light-years away, in the Draco constellation.

Astronomers were able to get an idea of its size through observing the dimming of the star it orbits when the planet passes in front. Scientists have now been able to establish the mass of the planet using an approach called the radial velocity technique.

Dr Nikku Madhusudhan, a lecturer at the Institute of Astronomy at the University of Cambridge, who was not involved in the study, explains:

"They were basically looking at the "wobble" of the host star that is caused by the gravitational tug from the planets in the system; so by looking at the wobble of star itself one can figure out the masses of the various planets in the system".

Kepler-10c is remarkable not only for its size, but its age. The star it orbits is 11 billion years old, meaning it formed just a few billion years after the Big Bang. This puts the dense giant at over double the Earth's age, another record breaker for a rocky planet. This could impact our search for extra terrestrial life, as Madhusudhan continues:

"This tells us that rocky terrestrial planets out there could be really old, much older than the earth. This puts a limit, if there was life at some point in the Universe, on how far back this life could have begun on planets like this."

Kepler-10c itself isn't a candidate for alien inhabitants, likely being too large and too hot to sustain life, but it reveals that life out there could have begun long before the Earth even formed.

Kepler-10c Giant Earth Interview - Madhu Madhusudhan

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