17/10/2012 09:24 BST | Updated 16/12/2012 10:12 GMT

Mysterious Earth-Sized Planet Discovered Close To Our Solar System

An Earth-sized planet has been found startlingly close to our solar system.

The world orbits Alpha Centauri B, a sun located just four light years away from our own.

It is the closest planet found outside our solar system.

However while the planet is similar in mass to Earth, it is much hotter - with surface temperatures of around 1,500 degrees C.

It would be too hot to support life, but scientists think it is likely just one of several planets in the system - one of which might be able to support life or human explorers - were it possible to get there.

Researchers at the European Southern Observatory's La Silla facility in Chile reported the find in Nature.

They said the planet forms part of a complex system of suns, including Alpha Centauri A and B which are roughly the size of our own Sun, and Proxima Centauri, a more faint red star.

The find has been described as "extraordinary" by the team from Geneva Observatory in Switzerland.

They were the same team that discovered the first confirmed planet outside our solar system in 1995. More than 800 so-called exoplanets have been found since.

The latest of those was located by detecting small shifts in the movement of the star caused by the gravity of the planet.

The observation showed that the planet is light, with only about the same mass as Earth - and is by far the lightest planet discovered outside our Solar System.

It cannot be seen directly by telescopes, but is thought to orbit the star at a distance of just six million kilometres, which is closer than Mercury is to our Sun.

With current tech it would take about 40,000 years to get to Alpha Centauri - but the team say they are confident humans may one day be able to travel there.

"Alpha Centauri B is of course a very special case - it's our next door neighbour," Stephane Udry of the Observatory in Geneva, told the BBC.

"So even if the discovery just stands perfectly normally in the discoveries we have had up to now, it's a landmark discovery, because it's very low-mass and it's our closest neighbour."