Frozen planet raises hope of life among stars

A frozen Earth-like planet circling just one of a pair of stars has greatly improved the prospects of finding extra-terrestrial life, astronomers claim.
Alien hunters: More locations have been foundAlien hunters: More locations have been found
Alien hunters: More locations have been found

Until the discovery, no-one realised that rocky planets could form stable orbits round one member of a binary star system. Planets orbiting pairs of binary stars are relatively common.

US astronomer Professor Scott Gaudi, from Ohio State University, said: “This greatly expands the potential locations to discover habitable planets in the future.

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“Half the stars in the galaxy are in binary systems. We had no idea if Earth-like planets in Earth-like orbits could even form in these systems.”

The new planet, located 3,000 light years away, is twice as massive as Earth and almost exactly the same distance from its parent star as the Earth is from the Sun. Because the host star shines 400 times less brightly than the Sun it is a frozen and almost certainly lifeless world.

But the astronomers point out that the same planet orbiting a Sun-like star would be in the “habitable zone” where conditions are potentially suitable for liquid water and life.

Prof Gould led four international teams reporting on the discovery in Science.

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The planet was found by chance when scientists spotted an unusual signal in light from a “microlensing” event, when a star’s gravity acts like a giant lens, bending light from a much more distant object precisely behind it.

In this case, the binary system disturbed light from a star 20,000 light years away.

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