Henbury Meteorite BM2003,M5

Henbury Meteorite BM2003,M5

This Iron meteorite was found in the Henbury Meteorites Conservation Reserve, Northern Territory, Australia. The Henbury Meteorites Conservation Reserve is a series of craters created by a meteorite event that happened around 4.7 thousand years ago. This sample was found in 1931 as part of the first scientific investigations of the site.

At Henbury there are at least 13 craters. They range from 7 to 180 metres in diameter, with the largest measuring 15 metres in depth. The craters were formed as multiple meteorites struck the Earth from the same fall. It was originally a single meteoroid, but it broke apart under the tremendous stress put upon it from travelling at incredible speed through the Earth's atmosphere. Several tonnes of iron-nickel fragments have been recovered from the site in total.

Classified as an Octahedrite, this Iron meteorite is made up of iron-nickel alloy, also known as meteoric iron. Iron meteorites are rarer than Stony meteorites, but due to the material they are made from they are easier to identify. They are believed to originate from the cores of ancient asteroids that have broken apart after colliding with other objects in space. This Henbury sample has nice examples of regmaglypts - thumbprint style imprints on the surface of the meteorite, caused by the fiery journey through the Earth's atmosphere. As the object speeds towards Earth, it heats up due to the pressure and friction of passing through the atmosphere. The surface gets so hot that it melts and experiences ablation. Ablation is the removal of material from the surface of an object, in this case by vaporisation. As the surface gets hot, a thin layer begins to melt, and, as the meteor rotates, bits of material vaporise. It quickly cools as it slows down, which leaves the distinctive thumbprint marks on the surface of the meteorite that can be seen on this Henbury sample.

Web resources

• Natural History Museum Website