Where are meteorites found?
Meteorites fall almost randomly over the Earth's surface, but often are lost - by falling into the ocean, or among other rocks.
Many meteorites are recovered from deserts (both cold and hot),
as the dry environment ensures their preservation, and the lack
of vegetation enhances their chance of being found.
Illustrations
How big is a meteorite, and how often do they fall?
Meteorites come in all sizes, from the very tiny - about one thousandth of a millimetre across - to the very large; bigger than a house. The smallest ones - micrometeorites - fall all the time: approximately 40,000 tonnes fall on the Earth each year. The very big ones only fall every million years or so. Meteor Crater in Arizona was produced by the impact of an iron meteorite about 50,000 years ago. The original meteorite was estimated to weigh up to about 25 000 tonnes, and would have been about ten metres across. However, most of it was vaporised on impact. It is likely that a really big meteorite fell at Chicxulub, in the Gulf of Mexico about 65 million years ago - the environmental changes caused by this impact might have resulted in the extinction of the dinosaurs.
To the right is a photomicrograph of a glassy micrometeorite,
approximately 50 microns in diameter. This specimen was collected
from Antarctic ice melt-water.
Several thousand in-between size meteorites, about the size of
a bag of sugar, fall on the Earth every year, but only five or six
are seen to fall and are brought to museums. No-one has been killed by
a falling meteorite, but they can do a lot of damage: the Peekskill
meteorite fell in New York State in 1993, landing in the boot
of a car!
The picture on the right is of Mr. Pettifor holding the last meteorite
to fall in England in 1991. The meteorite fell in the Pettifor's garden in Glatton, near Peterborough.
Illustrations
