TORONTO – Astronomers have discovered the first Earth-sized exoplanet, but it’s unlikely that we’ll find E.T. there.
In fact, how a planet formed so close to a star still remains a mystery to astronomers.
“It couldn’t have formed in place because you can’t form a planet inside a star. It couldn’t have formed further out and migrated inward, because it would have migrated all the way into the star. This planet is an enigma,” said Harvard Smithsonian Center for Astrophysics (CfA) astronomer Dimitar Sasselov, who was part of the research team.
“This planet is a complete mystery,” said astronomer David Latham of CfA. “We don’t know how it formed or how it got to where it is today. What we do know is that it’s not going to last forever.”
The planet is so close to the star, that eventually it will be pulled toward it, pulling the world apart.
“Kepler-78b is going to end up in the star very soon, astronomically speaking,” said Sasselov.
Kepler 78b flies around its star every 8.5 hours, at a distance of less than a million kilometres. For comparison, Mercury orbits the sun at a distance of 69,816,900 km (at its farthest), has an orbital period of 88 days.
The planet is 1.2 times larger than Earth and 1.7 times more massive, which indicates that the density of Kepler 78b is the same as Earth’s. This also tells astronomers that it is likely made primarily from rock and iron.
Kepler 78b (the star it orbits is Kepler 78 and b denotes the second planet in its system) was discovered using the Kepler space telescope. The telescope has since monitored 150,000 stars looking for planets that cross, or transit, stars.
The star, Kepler 78 can be found in the constellation Cygnus and is 400,000 light-years from Earth.
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