A team of French and Swiss astronomers working at the La Silla observatory in Chile discovered a planet about the size of Neptune located some 20.5 light years from our solar system, the European Southern Observatory said on Wednesday.
The still unnamed planet is located in the Libra constellation and has about 17 times the mass of the Earth. It takes only 5 days to complete its orbit around a star that has about a third the mass of the Earth's sun, the press release said.
The star G1 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, said in a statement. "This tells us that red dwarfs are key in the search for exoplanets," referring to planets circling other stars.
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 called HARPS that astronomers installed in the telescope of the observatory in north central Chile.
The planet orbits at only 3.7 million miles (6 million km) from its star, which leads scientists to estimate its surface temperature at about 302 degrees Fahrenheit (150 degrees centigrade).
Mercury, the planet closest to the sun, by comparison is 36 million miles (58 million km) from the sun and its orbit takes 88 days.