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'Too hot' Earth-sized planets discovered
Source: Agencies |
December 22, 2011, Thursday
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ASTRONOMERS have found a pair of Earth-sized planets orbiting a star similar to the sun, though neither is believed to be suitable for life, according to scientists on NASA's Kepler telescope team.
This follows confirmation this month of a super-Earth sized planet, called Kepler-22b, that circles the right distance from its parent star for liquid water to exist on its surface. Water is believed to be a key ingredient for life.
"Kepler-22b has the right temperature, but it is too big. (The planets) we're announcing today are just the right size, but too hot," said astronomer David Charbonneau with Harvard University.
"But you can bet the hunt is on to find a planet that combines the best of both worlds, a true Earth twin," he said.
The newly discovered planets in the constellation Lyra, Kepler-20e and 20f, have at least three gas-giant siblings.
But unlike our solar system - where rocky worlds like Venus, Earth and Mars are grouped together closer in towards the sun, while gas giants such as Jupiter and Saturn are in the outer regions - the planets in the Kepler-20 family are interspersed and all orbit closer to the parent star than our solar system's innermost planet, Mercury.
"This is the first time we've seen anything like this," Charbonneau said.
Kepler-20e and 20f, which are believed to be too hot for liquid water, probably are not habitable - at least not today.
"If Kepler-20f was formed with water, it could have held on to its water for several billion years," said astronomer Linda Elkins-Tanton with the Carnegie Institute in Washington DC. "It could have been habitable for a long period."
The system is 1,000 light-years away.
This follows confirmation this month of a super-Earth sized planet, called Kepler-22b, that circles the right distance from its parent star for liquid water to exist on its surface. Water is believed to be a key ingredient for life.
"Kepler-22b has the right temperature, but it is too big. (The planets) we're announcing today are just the right size, but too hot," said astronomer David Charbonneau with Harvard University.
"But you can bet the hunt is on to find a planet that combines the best of both worlds, a true Earth twin," he said.
The newly discovered planets in the constellation Lyra, Kepler-20e and 20f, have at least three gas-giant siblings.
But unlike our solar system - where rocky worlds like Venus, Earth and Mars are grouped together closer in towards the sun, while gas giants such as Jupiter and Saturn are in the outer regions - the planets in the Kepler-20 family are interspersed and all orbit closer to the parent star than our solar system's innermost planet, Mercury.
"This is the first time we've seen anything like this," Charbonneau said.
Kepler-20e and 20f, which are believed to be too hot for liquid water, probably are not habitable - at least not today.
"If Kepler-20f was formed with water, it could have held on to its water for several billion years," said astronomer Linda Elkins-Tanton with the Carnegie Institute in Washington DC. "It could have been habitable for a long period."
The system is 1,000 light-years away.
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