Amateur astronomers have for the first time spotted an asteroid that comes close enough to earth to pose a threat of impact. Volunteers picked out the cosmic rock - named asteroid 2011 SF108 - last month from the observatory in the Canary Islands. The breakthrough discovery could signal the first of many more asteroid sighting around the world as keen amateurs become more equipped with advanced technology.

Amateur astronomers have for the first time spotted an asteroid that comes close enough to earth to pose a threat of impact. Volunteers picked out the cosmic rock - named asteroid 2011 SF108 - last month from the observatory in the Canary Islands. The breakthrough discovery could signal the first of many more asteroid sighting around the world as keen amateurs become more equipped with advanced technology. Space experts said the sighting highlighting the value of ‘crowd-sourcing’ to science and planetary defense. The discovery of asteroid 2011 SF108 was made by the volunteer Teide Observatory Tenerife Asteroid Survey (TOTAS) team during an observation slot sponsored by ESA’s Space Situational Awareness (SSA) program. The four-night survey used the 1m-aperture telescope at ESA’s Optical Ground Station at Teide on Tenerife in the Canary Islands. This is not the first asteroid found under SSA sponsorship, but it is the first that qualifies as a ‘near Earth object’ – an object that passes close enough to Earth during its orbit around the Sun that it could pose an impact threat. During TOTAS observations, the telescope runs automated asteroid surveys for several hours using software developed by amateur astronomer and computer scientist Matthias Busch from the Starkenburg Amateur Observatory in Heppenheim, Germany. However, potential sightings must still be evaluated by humans. A team of 20 volunteers analyses each of the images to highlight anything that appears to be moving through space. The team successfully picked out the anomaly during the session on 28/29 September and it was was later confirmed as an asteroid. Detlef Koschny, Head of asteroid activity for SSA, said: 'Images are distributed to the entire team for review, and any one of them could be the discoverer of a new asteroid. This time, the luck of the draw fell to Rainer Kracht. 'As volunteer work, it is very rewarding. When you do spot something, you contribute to Europe’s efforts in defending against asteroid hazards.' 'When you do spot something, you contribute to Europe’s efforts in defending against asteroid hazards.' The orbit of asteroid 2011 SF108 brings it no closer than about 30 million km to Earth – a safe distance. The object is the 46th asteroid discovered by Mr. Kracht, a retired school teacher who lives in Elmshorn, near Hamburg, Germany. He said: 'Eight of us reviewed images on the night of the discovery, and I was lucky to be the one who found 2011 SF108 as part of this team. 'The discovery was only possible with the excellent software developed by Matthias Busch, who also spotted this object in the images on the second night and sent the observations to the Minor Planet Center.' To date, some 8000 asteroids have been discovered worldwide but many thousands more are suspected to exist, particularly in the size of meters to hundreds of meters. It is important to find and track these to determine if any pose an impact threat to Earth. TOTAS is helping to lay the foundation for a future European asteroid survey as part of the full SSA program, which is to be decided in 2012. Such a survey would use multiple 1m telescopes to scan the complete sky every night, a much larger effort than at present, and is expected to discover several asteroid per week. It would use a mix of professional and ‘crowd-sourced’ astronomers. Currently, professional asteroid surveys are performed only in the USA. The only significant asteroid survey in Europe now is the La Sagra Sky Survey, undertaken by amateur astronomers in southern Spain.