By By Kev Hedges Sep 28, 2010 in Science Astronomers have spotted a large and 'potentially hazardous' asteroid heading towards Earth and it is only less than a month away from passing within four million miles. The Pan-STARRS survey based at Haleakala, Maui uses a new telescope designed to scan the skies for asteroids likely to pass close to Earth. It is the first time it has detected a potentially hazardous object. 2010 ST3 is expected to be at its closest to Earth in mid-October. Robert Jedicke is a University of Hawaii member of the PS1 Scientific Consortium, he said: Although this particular object won't hit Earth in the immediate future, its discovery shows that Pan-STARRS is now the most sensitive system dedicated to discovering potentially dangerous asteroids. This object was discovered when it was too far away to be detected by other asteroid surveys. Most of the largest potentially hazardous objects have been catalogued. Scientists suspect there are many more under a mile across that have not yet been discovered. Large asteroids supposedly crash into Earth once every few thousand years. The object is 150 metres in diameter and has been named '2010 ST3'. It was discovered using the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) PS1 telescope in images taken on Sept 16 reports Mail Online , when it was about twenty million miles away.The Pan-STARRS survey based at Haleakala, Maui uses a new telescope designed to scan the skies for asteroids likely to pass close to Earth. It is the first time it has detected a potentially hazardous object. 2010 ST3 is expected to be at its closest to Earth in mid-October.Robert Jedicke is a University of Hawaii member of the PS1 Scientific Consortium, he said:Most of the largest potentially hazardous objects have been catalogued. Scientists suspect there are many more under a mile across that have not yet been discovered.Large asteroids supposedly crash into Earth once every few thousand years. More about Asteroid, Telescope, Space, Earth asteroid telescope space earth