SANTIAGO - Astronomers have discovered an exoplanet orbiting a star much like the Sun, the European Southern Observatory (ESO), located in Chile's northern desert, said on Wednesday.

Three planets orbiting stars have been discovered in the cluster Messier 67, which contains about 500 stars. The cluster lies about 2,500 light years away in the constellation of Cancer, where one of the planets orbits a star very similar to our Sun, the ESO said in a statement.

"The first planet (of the three) proved to be orbiting a remarkable star. It is one of the most similar solar twins identified so far and is almost identical to the Sun. It is the first solar twin in a cluster that has been found to have a planet," said the statement. An exoplanet is defined as the planet that orbits stars outside our Solar System.

Despite the fact that more than 1,000 exoplanets have been detected outside the Solar System, very few planets have been found so far inside star clusters.

The results were supplemented with observations from several other observatories around the world.

"The team carefully monitored 88 selected stars in Messier 67 over a period of six years to look for the tiny telltale motions of the stars toward and away from the Earth that reveal the presence of orbiting planets," said Anna Brucalassi, the leading author of the study.

"In the Messier 67 star cluster the stars are all about the same age and composition as the Sun. This makes it a perfect laboratory to study how many planets form in such a crowded environment," added Brucalassi, who works at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

The ESO operates three sites in the Atacama desert, 500 km north of the capital Santiago.