Potentially habitable planet found practically in our back-yard

Posted by Emma Woollacott

Astronomers have at last discovered a nearby Earth-like planet that could easily have liquid water - and life.

The newly-discovered super-Earth is part of a system initially thought to have three planets, but now found to have six. And while the first three were too close to the star to contain liquid water, one of the new ones sits squarely in the star's habitable zone.

"We pioneered new data analysis techniques including the use of the wavelength as a filter to reduce the influence of activity on the signal from this star," says  Mikko Tuomi of the University of Hertfordshire.

"This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star known as HD 40307, making it into a six-planet system."

The really exciting find is the planet that's furthest from the star, HD 40307g, which has a mass at least seven times that of Earth. It orbits its star at a similar distance to Earth’s orbit around the sun, so receives a similar amount of energy.  

 Here, liquid water and a stable atmosphere to support life are perfectly possible, and - even more importantly - the planet is likely to be rotating on its own axis as it orbits its star, giving it a day and night like Earth's.

"The star HD 40307, is a perfectly quiet old dwarf star, so there is no reason why such a planet could not sustain an Earth-like climate," says Guillem Anglada-Escude of the University of Goettingen.

A planet with a similar orbit, Kepler 22 d, was discovered earlier this year. But it's 600 light years from Earth, whereas this new super-Earth is just 42 light years away.

And that means that it could be directly observable within just a few years.

"Discoveries like this are really exciting, and such systems will be natural targets for the next generation of large telescopes, both on the ground and in space," says David Pinfield of the University of Hertfordshire.