An amazing haul of 32 new planets was revealed today. The alien worlds orbiting other stars were all discovered by a planet-hunting instrument at the European Southern Observatory 2,400 metres above sea level in Chile’s Atacama desert.
The device is fitted to a telescope with a giant “eye” – a mirror 3.6 metres wide (11.8 ft) – to collect light from distant suns. Its long list of new finds was announced at a conference of planet-seeking astronomers at Porto, Portugal, and simultaneously at another astronomical gathering in Madrid.
The detector, called the High Accuracy Radial Velocity Planet Searcher (HARPS), works by watching tiny changes in the spectrum of starlight. These indicate that the star is wobbling as one or more exoplanets that we cannot see directly orbit around it.
The latest discoveries make HARPS the clear leader in planet-hunting. In five years of operation, it has now spotted more than 75 of the 400 or so exoplanets found in alien solar systems.
It has been particularly successful in finding smaller planets only a few times more massive than the Earth, rather than just giant gas worlds called “hot Jupiters”.
In fact 24 of the 28 planets known which are less than 20 times the size of Earth have been found with HARPS. Most of these smaller planets have been found in star systems that have a number of planets with up to five per star.
Stéphane Udry, of Geneva Observatory, announced the latest discoveries. He said: “HARPS is a unique, extremely high precision instrument that is ideal for discovering alien worlds. We have now completed our initial five-year programme, which has succeeded well beyond our expectations.”
HARPS’ success is being challenged by other hunts using NASA’s Kepler space telescope and automatic camera surveys on the ground, such as Pan-STARRS and SuperWASP, that watch for dips in starlight, or transits, as planets pass in front of them.
Picture: One of the new planets detected is about six times as massive as the Earth and orbits a star called Gliese 667 C, which belongs to a triple system.Two of the stars can be seen in this artist’s impression. (Credit: ESO/L. Calçada).
• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available.