Planet-hunters have made a major breakthrough by discovering the first Earth-sized rocky world that could support life. Attempts have already been made with radio telescopes to listen in to the planet for any signals from ET, as you can read in my full report on the discovery on the space website Sen.

The new planet was detected using NASA’s Kepler space telescope and lies 490 light-years away in the constellation of Cygnus. They spotted the tiny dip in light as it passed in front of its own sun.

It is orbiting a red dwarf star called Kepler 186 and is the fifth planet spotted in that planetary system. Unlike the others, it lies in the star’s habitable zone, where water vital to life could exist as a liquid on the surface. There is no guarantee, however, that it is Earth-like.

Two giant telescopes on Hawaii confirmed the discovery of the planet, which is labelled Kepler-186f. Scientists from the SETI Institute – it stands for Search for Extra-Terrestrial Intelligence – turned the radio dishes of the Allen Telescope Array in California towards the new planet to act like a super-sensitive ear. Sadly no alien broadcasts have yet been heard.

Though nearly 1,800 planets have been found around other stars, using various techniques, the vast majority have been giant balls of gas like Jupiter. And only about 20 have been detected in their home stars’ habitable zones, and they have all been bigger than our Earth.

The discovery team was led by SETI’s Elisa Quintana based at NASA’s Ames Research Centre in California. She said: “This is the first definitive Earth-sized planet found in the habitable zone around another star.”

Check out my full story at Sen.