One of the new planets orbits the star Gliese 667 C, which belongs to a triple-star system. The planet, which is six times the mass of Earth, orbits at only 1/20th the distance that the Earth is from the Sun. The star has two other low mass companion stars, seen here in the distance.
Credit: ESO
PARIS: Astronomers have announced the discovery of 32 new planets outside our Solar System, some of them only a few times larger than Earth.
The relatively small size increases the odds that these exoplanets could have conditions similar to the ones that gave rise to life on Earth.
Scientists made the finds using the High Accuracy Radial Velocity Planet Searcher, or HARPS, the most successful low-mass exoplanet hunter in the world.
HARPS success
The HARPS spectrograph is attached to the European Southern Observatory's (ESO) 3.6-metre telescope at La Silla, Chile.
The findings, presented at an exoplanet conference in Porto, Portugal on Monday, raises the number of known exoplanets to more than 400, a fifth of them - from 30 different planetary systems - uncovered by HARPS.
Most are giant balls of toxic gas similar to Jupiter, and thus would be inhospitable to life as we know it. But 28 are so-called "super-Earths" with masses 20 times the size of Earth or less, and are thus probably rocky planets, the ESO said.
Goldilocks zone
Whether any harbour carbon-based life forms would depend in part where they orbit in relation to their stars.
Earth sits in a so-called 'Goldilocks zone' where the temperature is neither too hot for our atmosphere to be stripped away, nor too cold for our seas to freeze - but just right to have liquid water, the stuff of life.
HARPS was designed and built by a team from the Geneva Observatory led by Michel Mayor, who unveiled their most recent findings.
"We have now completed our initial five-year program, which has succeeded well beyond our expectations," said Stephane Udry, a researcher at the University of Geneva. No particularly Earth-like planets were discovered in the group that was announced Monday, he said.
As with the previously detected super-Earths, most of the new low-mass candidates reside in multi-planet systems, with up to five planets per system.
