New planets discovered outside Solar System

Swiss researchers have announced the discovery of three "super-Earths" orbiting a nearby star, as well as two other solar systems with small planets.

They said their findings, presented at a conference in Nantes, France, on Monday, suggest that Earth-like planets may be very common.

“Does every single star harbour planets and, if yes, how many?” asked Michel Mayor of Geneva Observatory. “We may not yet know the answer but we are making huge progress towards it,” he said in a statement.

The trio of planets orbit a star slightly less massive than our Sun, 42 light years away towards the southern Doradus and Pictor constellations. A light year is the distance light can travel in one year, about 9.5 trillion kilometres.

The planets are bigger than Earth – up to 9.4 times the mass – and orbit their star at extremely rapid speeds. The slowest takes just 20 days compared with Earth’s 365.

Mayor and colleagues used the High Accuracy Radial velocity Planet Searcher (Harps), a telescope at La Silla observatory in Chile, for their search.

More than 270 so-called exoplanets have been found. Most are giants, resembling Jupiter or Saturn. Smaller planets closer to the size of Earth are far more difficult to spot.

None can be imaged directly at such distances but can be spotted indirectly using radio waves or, in the case of Harps, spectrographic measurements. As a planet orbits, it makes the star wobble very slightly and this can be measured.