Over the last couple of weeks, our meteorites had been having a busy time. On Friday 11th May, groups of Oxford University geology students came across to the Museum to have tutorials with Dr Don Porcelli from the Department of Earth Sciences. It’s a great opportunity for them to handle and study ten of our most interesting meteorites, and is always very popular. As one of them, Freya, wrote in the Oxford Undergraduate Prospectus last year, ‘There can’t be many subjects where you are able to hold an actual piece of Mars in a meteorite tutorial!’.
Most meteorites come from the asteroid belt, a band of rocky debris between Mars and Jupiter. The lumps of rock keep colliding, and now and again that sends pieces spinning in the direction of Earth. Tiny fragments burn up as they enter the Earth’s atmosphere, and we see them as meteors – shooting stars. Larger pieces reach the surface of the Earth, and they are known as meteorites. Even bigger pieces hit the Earth with such explosive force, they all but vaporise… but that is another story!
The interesting thing about the asteroid belt meteorites is that they are made of the same planetary debris that the Earth itself was formed from, some 4.5 billion years ago. However as Freya pointed out, one of our meteorites has more exotic origins. The Nakhla meteorite fell at Nakhla, in Alexandria, Egypt on 28th June 1911. Isotope and trace element analyses have shown that it is almost certainly from Mars. The fall allegedly killed a dog; as one of my students once put it, the only Earthling to be killed by a Martian. Meteorites from Mars are exceptionally rare, and give a very special insight into the rocks that make up another planet.
Last Tuesday, members of the public had a peek behind the scenes on one of our regular Tuesday afternoon tours. The theme was ‘Rocks from Earth and Space’, and leader, Dr Dave Waters, showed them some historic rocks from Greenland and Everest, as well as those meteorites. Just think of all those people saying this week that they’ve just held a little piece of real Mars rock!
Monica Price, Assistant Curator, Mineral Collections