A team of French and Swiss astronomers has discovered a planet 20.5 light years from our solar system.
The unnamed planet was spotted by scientists at the La Silla observatory in Chile, said the European Southern Observatory on Wednesday.
The planet is located in the Libra constellation and has about 17 times the mass of the Earth. It takes only five days to complete its orbit around a star that has about a third the mass of the Earth's sun, a statement said.
The star - Gl (Gliese) 581 - is a red dwarf, a small, cool, faint star that is the most common type in our galaxy.
Since 80 of the 100 stars closest to the sun are red dwarfs, astronomers are interested in discovering if they have planets orbiting them.
"Our discovery could mean that planets orbiting small stars are common," said Xavier Delfosse, a member of France's Grenoble Astrophysics Laboratory.
"This tells us that red dwarfs are key in the search for exoplanets," he said, referring to planets circling other stars.
Ten years ago two Swiss astronomers, Michel Mayor and Didier Queloz, who are part of the team in Chile, discovered the first planet outside our solar system.
Of the currently known 170 planets circling other stars, only five of them are smaller than this newly discovered planet.
The discovery was made possible by a high precision instrument that astronomers installed in the telescope of the observatory in north central Chile.
The planet orbits at only six million kilometres from its star, which leads scientists to estimate its surface temperature at about 150 degrees Celsius.
Mercury, the planet closest to the sun, by comparison is 58 million kilometres from the sun and its orbit takes 88 days.
swissinfo with agencies
The team of astronomers is made up of scientists from France and the Geneva Observatory in Switzerland.
Among them are the Swiss Stéphane Udry, Michel Mayor, Francesco Pepe and Didier Queloz.
Mayor and Queloz were the first astronomers to discover a planet outside our solar system in 1995.