Astronomers are over the moon after discovering the first ever Earth-sized planet orbiting a star – in our neighbouring solar system.
For centuries scientists have speculated that planets could orbit Alpha Centauri, a group of three stars which are among the brightest in the southern skies.
But despite improved technologies their searches had failed – until the discovery of this ‘exoplanet’.
The newly-discovered planet is around 25.8 trillion miles away – 4.3 light-years – which in galactic terms is the equivalent of being next door.
It is the first ever Earth-sized planet discovered anywhere in the universe and it orbits a star similar to the Sun – but this is where the similarities end.
The planet, which is about six million kilometres away from Alpha Centauri B, orbits the star every 3.6 days.
This is much closer than Mercury is to the Sun in the Solar System with scientists estimate the temperature to be around 1,200-degrees centigrade.
However, the “exciting” discovery raises hopes that astronomers will find an exoplanet planet within the habitable zone of Alpha Centauri – a distance which may possibly be able to support some sort of life.
Scientists from the European Southern Observatory made the discovery using the HARPS instrument on the 3.6-metre telescope at its La Silla Observatory in Chile.
They detected the planet by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet.
Stéphane Udry, from the Geneva Observatory, said: “This is the first planet with a mass similar to Earth ever found around a star like the Sun.
“Its orbit is very close to its star and it must be much too hot for life as we know it.
“But it may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems.”
Xavier Dumusque, from the Geneva Observatory, said the breakthrough was an “extraordinary discovery”.
He said: “Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days.
“It’s an extraordinary discovery and it has pushed our technique to the limit.
“This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun. We live in exciting times.”
It raises hope astronomers will find an exoplanet planet within the habitable zone of Alpha Centauri – a distance which may possibly be able to support some sort of life.
The first exoplanet orbiting a star was discovered in 1995 and another 800 have been located since then, with most around the same size as Jupiter.