Super-Earth found within ‘Goldilocks’ zone of star

A “super-Earth” that could have a life-supporting climate has been discovered in a multi-world solar system 42 light years from the sun.

The planet, which is several times bigger than the Earth, lies just the right distance from its star to allow the existence of liquid surface water.

It orbits well within the star’s “habitable” or “Goldilocks” zone — the region where temperatures are neither too hot nor too cold to sustain life.

The new world is one of six, all with masses a few times that of the Earth, believed to circle the dwarf star HD 40307 in the constellation Pictor.

All the others are located outside the habitable zone, too close to their parent star to support liquid water.

Three of these were originally identified in 2009 by European Southern Observatory astronomers.

They used an instrument called Harps (High Accuracy Radial Velocity Planet Searcher) to look for changes in the colour of starlight that give away the presence of planets.

A new analysis of the Harps data, using special computer software, has now revealed three more super-Earths.

One of them, HD 40307g, excited astronomers because it was much further from the star than its companions — between half and three quarters of the Earth’s distance from the sun — and comfortably within the habitable zone.

Prof Hugh Jones, from the University of Hertfordshire in England and a member of the international team, said the longer orbit of the new planet means that its climate and atmosphere may be just right to support life.

“Just as Goldilocks liked her porridge to be neither too hot nor too cold but just right, this planet or indeed any moons that it has lie in an orbit comparable to Earth, increasing the probability of it being habitable.”

Scientists believe the planet turns on its axis, giving it a regular day and night cycle and making its environment even more Earth-like.