Nasa scientists have opened up a fascinating new field of observing for amateur astronomers – meteor impacts on the Moon. The space agency has found that impacts powerful enough to be seen from Earth happen surprisingly frequently. At least five were recorded as flashes of light on one night last month.

Nasa expert Bill Cooke recorded the blasts, ranging in power from 50 to 125 lbs of TNT, as the Earth passed through a cloud of debris left by a Near Earth Asteroid called Phaethon.

The asteroid is well known as the source of a major meteor shower called the Geminids every year in mid-December. Meteoroid particles burn up before reaching the ground on Earth.

The impacts from the same shower on the moon were spotted on December 14. There is no atmosphere on the moon and so the meteors struck the ground at around 78,000mph.

Cooke, of Nasa’s Meteoroid Environment Office in Huntsville, Alabama, said: “At that speed, even a pebble can blast a crater several feet wide. The flash of light comes from rocks and soil made so hot by impact that they suddenly glow. We saw about one explosion per hour.”

Cooke’s group watched the moon using two 14-inch telescopes linked to specialist CCD digital cameras. They were surprised when they first snapped a meteor impact on the moon in late 2005 but have recorded another 18 since.

Nasa are now urging amateur astronomers to use similar top-of-the-range telescopes and off-the-shelf cameras to help monitor the moon for more impacts. They want to assess the risk to astronauts in a lunar colony.

Cooke said: “A worldwide network of amateurs, watching the moon whenever possible, would increase the number of explosions we catch.”

Personally I think it is a great shame that we were not aware of the phenomenon back in 1998 when the November Leonids put on a tremendous “night of the fireballs”. Surely they would have produced some fantastic flashes on the Moon.