http://news.bbc.co.uk/2/hi/science/nature/3856401.stm By Dr David Whitehouse BBC News Online science editor The Hubble Space Telescope may have discovered as many as 100 new planets orbiting stars in our galaxy. Hubble's harvest comes from a sweep of thousands of stars in the dome-like bulge of the Milky Way. If confirmed it would almost double the number of planets known to be circling other stars to about 230. The discovery will lend support to the idea that almost every sunlike star in our galaxy, and probably the Universe, is accompanied by planets. 'Most significant advance' Steven Beckwith, director of the Space Telescope Science Institute, told BBC News Online: "I think this work has the potential to be the most significant advance in discovering extra-solar planetary systems since the first planets were discovered in the mid-1990s. "If it works, it will be a breakthrough for the field, and it will make Hubble one of the most important instruments to find new planetary systems." The planets were found during a seven-day observation period in February by astronomer Kailash Sahu. Some of the stars observed were seen to dim slightly in brightness. It is thought that a planet passing in front of the star is responsible for the dip in its light output. "Discovery of many planets near stars in the bulge of the galaxy would clearly demonstrate that planetary systems are very common around normal stars," Mr Beckwith said. More work remains to be done to convince astronomers that they really have found so many new planets. "We are not likely to have final results until this fall, perhaps September or October," Mr Beckwith added. "We need to confirm some of the candidate planets discovered around the brighter stars by using well known radial velocity techniques from the ground, a process that will take a few weeks. There is further analysis of the Hubble images to do as well." The astronomers expect it should be possible to study the atmospheres of between 10% and 20% of the planets discovered. The US space agency Nasa is studying options to refurbish the Hubble telescope using unmanned spacecraft following a decision earlier this year that, in the wake of the Columbia disaster, it was too dangerous to send astronauts to it on the space Shuttle.