Proxima B 'May Well' Harbour Life: New Study Claims 'Second Earth' Just Four Light Years Away Has Oceans And A Thin Gassy Atmosphere.

It is estimated to have a mass about 1.3 times that of Earth, and orbits about 7.5 million kilometres (4.6 million miles) from its star—about a tenth the distance of innermost planet Mercury from the Sun.

Contrary to what one might expect, such proximity does not necessarily mean that Proxima b's surface is too hot' for water to exist in liquid form, said a CNRS statement.

Proxima Centauri is smaller and 1,000 times weaker than our Sun, which means Proxima b is at exactly the right distance for conditions to be potentially habitable.

The planet may very well host liquid water on its surface, and therefore also some forms of life,' the statement said.

In a study to be published in The Astrophysical Journal Letters, an international team led by researchers at the Marseille Astrophysics Laboratory (CNRS / Aix-Marseille Université) has determined its dimensions.

The size of exoplanets are generally calculated by measuring how much light they block out, from Earth's perspective, when they pass in front of their host star.

But no such transit of Proxima b has yet been observed, so the team had to rely on simulations to estimate the planet's composition and radius.

They calculated the radius was between 0.94 and 1.4 times that of Earth, which is 6,371 kilometres on average.

Assuming a minimum radius of 5,990 km, the planet would be very dense, with a metallic core making up two-thirds of the entire planets mass, surrounded by a rocky mantle.

If there is surface water, it would   not contribute more than 0.05 percent to the planet's total mass, the team said—similar to Earth, where it is about 0.02 percent.

In the larger planet scenario, with a radius of 8,920 km, Proxima b's mass would be split 50-50 between a rocky centre and surrounding water.

Distance: This is the closest Earth-like planet we could ever find. Orbiting our nearest star, the planet is only four light years away.

Missions to send spacecraft to the planet to examine for signs of life are already in planning, and could happen within decades.

Composition: The planet is rocky and a similar size to Earth.

Temperature: It lies in the 'habitable zone' of its star, which means there could be liquid water on its surface - a key ingredient for alien life.

The temperature on the surface of the planet could be between -90° and 30° Celsius (-130 and 86 Fahrenheit).

Atmosphere: If Proxima b has an atmosphere, the simple ingredients - water, carbon dioxide, and rock - that are needed for the formation of biochemical cycles that we call life, could all be present and interacting on the planet's surface.

'In this case, Proxima b would be covered by a single, liquid ocean 200 km deep,' said the CNRS.

'In both cases, a thin, gassy atmosphere could surround the planet, like on Earth, rendering Proxima b potentially habitable,' it concluded.

Earlier this year, a group of researchers, using the European Southern Observatory (ESO) telescopes, have named the exciting world Proxima b.

Thousands of exoplanets have been discovered before, but unlike the others, this planet is within our reach.

While four light years is a long way - more than 25 trillion miles - future generations of super-fast space craft could conceivably travel to the planet within the next few decades.