Scientists have discovered two new ‘super-Earth’ planets which they say are potentially habitable.
They are among four newly discovered planets orbiting Tau Ceti, the nearest Sun-like star to Earth, some 12 light years away.
The two ‘super-Earths’ are located in the habitable zone of the star – the area that is not too hot and not too cold – which scientists believe could mean they support liquid surface water.
Scientists made the findings by observing wobbles in the movement of the star, caused by its orbiting planets.
Differences in the sizes of the movements, between 10 and 30 centimetres a second, are caused by planets or moons with environmental conditions similar to Earth.
Dr Fabo Feng, research fellow at the University of Hertfordshire and lead researcher on the study, said: “We’re getting tantalisingly close to observing the correct limits required for detecting Earth-like planets.
“Our detection of such weak wobbles is a milestone in the search for Earth analogues and the understanding of the Earth’s habitability through comparison with these.”
Stars the size of the Sun are the best targets for finding habitable Earth-seized planets.
Tau Ceti is similar to our Sun in both size and brightness, and like our Sun hosts a multi-planet system.
Scientists hope that direct imaging of the two outer planets could show them to be rocky and habitable.
The researchers concede, however, that a massive disc of debris around the star could be bombarding them with asteroids and comets, and therefore reducing their habitability.
“We’re slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface,” said Dr Mikko Tuomi, also from the university.
“This enabled us to verify the existence of the two outer, potentially habitable, planets in the system.”