Astronomers have discovered a planet that is a similar size to Earth orbiting a cool, dim star at just the right distance for liquid water to exist. It is the most Earth-like planet found so far that could potentially host life.

A team led by Elisa Quintana of the SETI Institute in Mountain View, California, discovered the planet, Kepler-186f, by looking at data from NASA's Kepler space telescope. Slight drops in a star's brightness revealed the orbiting planet, the fifth known in that particular system.

Kepler-186f is just 1.1 times the size of Earth and orbits its star every 130 days. It is towards the outer edge of the star's habitable zone — in our Solar System, it would be equivalent to putting Earth out near the orbit of Mars.

Science 344, 277–280 (2014)

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