Meteorites are rocks that are found here on Earth, but that originated from space. Meteorites come from bodies in the asteroid belt, the Moon or Mars that are on Earth-crossing orbits. They enter the Earth’s atmosphere as fireball (meteor) events, which can often be dramatic, being accompanied by high altitude breakup, flashes of bright light and shock waves. The surviving rock fragment can vary in size from a few cm to a couple of meters in size. The exterior of the meteorite is often super heated forming an ablated surface called a fusion crust (the colour depends on the type of meteorite, but this is often a characteristic black colour), but the interior of the stone survives the dramatic entry event.
Meteorites are recovered either as fall or finds – where falls are collected after a fireball event is witnessed, and finds are recovered a long time after the original entry event (often many thousands, to hundreds of thousands or even millions of years afterwards).
The science of meteorites is known as meteoritics – see here for more information about why scientists study these samples in their laboratories.
Meteorites from Antarctica. As of June 2018 there are currently just over 31,000 officially named meteorites that have been collected in Antarctica. This is 63% of the worlds total meteorite collection (nearly 50,000 stones classified in the world to date*.
Meteorites are recovered in Antarctica because they are well preserved in the cold and dry environment. They are also easy to spot as dark coloured rocks on the white ice. Most meteorites are found in blue icefields (known as Meteorite Stranding Zones) close to the Transantarctic Mountains and other mountain ranges like Grove Mountains and the Sør Rondane Mountains (see a map below). These localities concentrate meteorites that have traveled within large glaciers from the South Pole ice polar plateau, and are impeded by topographically high mountain ranges. The glaciers are slowed down in their progress, and the strong katabatic winds in these regions scour the ice surface revealing the meteorites that are trapped within. This model is known as the conveyor belt meteorite delivery system, although it doesn’t explain why some ice sheets are more productive in meteorite numbers than others.
Find out more here about how glacial flow and field settings influence if meteorites are carried within or become exposed on the surface of different Antarctic glaciers.
*Statistics from the Meteoritical Bulletin Database.