Meteorites can be separated into four main groups:
Chondrites are grainy stony meteorites composed mainly of silicate minerals like olivine and pyroxene. They make up about 80% of the meteorites found on Earth.
Achrondrites are similar to chondrites, but at some point in their lifetime they have been melted (like magma) and therefore they do not demonstrate the same graininess that chondrites do.
Iron meteorites are composed mainly of meteoric iron. Despite its name meteoric iron is actually an iron-nickel alloy, and most iron meteorites are composed of either kamacite or taenite.
The fourth and final group are the siderolites, stony-iron meteorites, and they are beautiful. I am particularly keen on pallasites, which contain centimetre-sized grains of peridot olivine embedded within a matrix of meteoric iron.
The origin of pallasites is uncertain, but it’s thought possible that they may be formed when two asteroids collide, or when a meteorite collides with the surface of a planet.
A meteor entered Earth’s atmosphere over the Alberta-Saskatchewan border on Thursday night and the first videos of its entry are starting to filter through onto YouTube.
This is some of the best meteor footage I’ve ever seen.
Barringer crater was formed about 50 000 years ago when a nickel-iron meteorite about 50 metres wide, with a mass of 150 million kilograms slammed into the ground in the Arizona desert at about 13 kilometres per second (about 29 000 miles per hour).
The energy released in the explosion is estimated to be equivalent to 2.5 megatonnes of TNT more than 150 times that of the atomic bomb dropped on Hiroshima. It would have killed anything living within a three or four kilometre radius.
The crater is over a kilometre wide (1200m) and 170m deep, with a 45m-high rim all the way around.