The crater, called Kamil, is positively pristine when compared to most holes in the Earth gouged by impacting meteorites. Where many craters on our planet are partially eroded, this one retains much of its structure, down to even the rays of ejected material that were shot from the centre, when the space rock hit. 

"This crater is so well-preserved that it will tell us a lot about small scale meteorite impacts on the Earth's crust," said study leader - Luigi Folco.  "It's so nice and neat. There is something extraordinary about it."

"Generally, craters this immaculate are found only on the moon or Mars, where there are fewer environmental or atmospheric processes to destroy them", he said.

Holes in the Earth

The Kamil Crater is 148 feet (45 metres) wide and was first spotted on Google Earth satellite photographs by Vincenzo de Michele, a former curator of the Civico Museo di Storia Naturale in Milan, Italy.

Based on the size and characteristics of the bowl shaped crater, the researchers think it was caused by the impact of an iron meteorite about 4.3 feet (1.3 meters) in diameter, travelling at 7,920 mph (11,732 kph).

To verify the discovery, a team of geophysicists, including Foldo, descended on the site in southern Egypt's Sahara desert in February 2010.

"We could see with our eyes that it was really well preserved and a potential source of detailed information about this kind of event," Folco told SPACE.com.

Folco was the lead author of a paper published in the July 23 issue of Journal Science, announcing the find.

Ancient crash

The scientists can't be sure how long ago the Kamil meteorite crash occurred. However, they estimate it was roughly a few thousand years ago.  This is relatively recent, in geological terms.

There are only about 175 confirmed Earth impact craters, even though the planet is barraged by space rocks slamming into it relatively often. Yet most craters are worn away easily on the ever-changing surface of Earth.

"This is important because small impacts are rather frequent on Earth.  One event occurs every 10 to 100 years," Folco said. "So studying this crater is a good opportunity for scientists to get a correct assessment of the hazard small impacts pose to the Earth and to devise mitigation strategies."

Objects about the size of washing machines typically fall into Earth's atmosphere every month, but most burn up before they can reach the ground. Many of the resulting fireballs are not seen, because they occur over remote areas or over the ocean. The Earth is more than two-thirds ocean.