Scientists have found a planet about 4.5 times the mass of Earth that orbits in the heart of its star's habitable zone, with two other suns orbiting much farther away. Is there water or the potential for life? Perhaps. But the planet could also be a two-faced world of scorching sun and perpetual ice.
A newfound planet only 22 light-years away represents the best candidate yet for hosting liquid water on its surface, according to a team of astronomers announcing the find Thursday.
The planet has 4.5 times Earth's mass and orbits in the heart of its star's habitable zone – the region where water could remain stable on an orbiting planet's surface. Liquid water is a necessary ingredient for organic life.
For now, however, too little is known about the planet's composition and the makeup of any atmosphere – if it has one – to say with confidence that water is likely to be there, researchers say. Location alone does not make for a habitable planet. Some scientists suggest that the newfound planet could be caught with one hemisphere permanently facing its star, lessening any prospects for life.
Still, the researchers note the planet's position well within the habitable zone is an encouraging first sign.
This is not the first so-called super Earth astronomers have detected in a star's habitable zone. In December, scientists with NASA's Kepler mission announced the discovery of a super Earth orbiting within its host star's habitable zone. That planet was orbiting a sun-like star, marking an important step along the path toward meeting the mission's goal of uncovering Earth-size planets orbiting within the habitable zone of sun-like stars.
But the new planet, GJ 667Cc, orbits a red dwarf – a type of star that is much smaller, fainter, and far more common in the galaxy than sun-like stars. Given red dwarfs' prevalence, the finding suggests that the galaxy should be brimming with super Earths in habitable zones, the research team says.
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