Planet that may hold life found ‘nearby’

A rocky planet that may harbour life has been discovered in another solar system just four light years from Earth, close enough to be reached by future space missions.

The new world, slightly more massive than Earth, orbits Proxima Centauri, our closest stellar neighbour.

In terms of astronomical distance, the planet known as Proxima b is right next door. Whether or not anything lives there remains open to speculation, but scientists believe that theoretically it could be habitable.

While four light years is a long way — more than 25trn miles — the planet is near enough to be reached by space craft within the scale of human life times.

Experts believe robotic probes could be sent to Proxima b in years to come. Much further in the future the planet may even be colonised by space travellers from Earth, assuming conditions are survivable.

One possible obstacle to life evolving and flourishing on the planet is the way it hugs its parent star. Proxima b is only 7.5m kilometres from the star, 5% of the distance between the Earth and the Sun, and takes just 11.2 days to complete one orbit.

But because Proxima Centauri is a dim red dwarf star radiating much less heat than the Sun, it still occupies the “habitable zone” where temperatures are mild enough to permit liquid surface water.

On the other hand the planet is blasted by powerful ultraviolet rays and X-rays from the star. Any life that evolved on its surface would have to be hardened against the radiation.

Nevertheless, the prospect of finding life on Proxima b has excited scientists.