Astronomers have discovered an earth-sized orbiting Proxima Centauri, the closest star to our solar system. Proxima Centauri is only 4.2 light years away, and the target planet - Proxima b - is just 1.17 times the size of Earth. The second Earth was discovered by an international team of scientists using the Very Large Telescope in Chile. It was detected four years ago using an older spectrograph attached to the telescope called HARPS, but a new Swiss-made spectrograph called ESPRESSO has allowed them to measure its size with never-seen-before accuracy.
The results of the team's study were published in the journal Astronomy & Astrophysics.
"We were already very happy with the performance of HARPS, which has been responsible for discovering hundreds of exoplanets over the last 17 years," said astronomer Francesco Pepe of the University of Geneva.
"We're really pleased that ESPRESSO can produce even better measurements, and it's gratifying and just a reward for the teamwork lasting nearly 10 years."
It's not clear yet if Proxima b could harbour life. It orbits its star in just 11.2 days, about 20 times closer than we are to the sun. But Proxima Centauri is a red dwarf and doesn't put out as much energy, so liquid water could very well exist on Proxima b.
However, Proxima Centauri lets off huge amounts of X-rays, which could pose a problem.
"Is there an atmosphere that protects the planet from these deadly rays?" said astronomer Christophe Lovis, also of the University of Geneva.
"And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favourable conditions existed?
"We're going to tackle all these questions, especially with the help of future instruments."
But don't expect to be going there anytime soon. The SpaceX craft which launched on Sunday morning (NZ time) reached a speed of 27,000km/h - even at that clip, it would take 168,000 years to reach Proxima Centauri.
