Pieces that survive the journey and
hit the ground are called meteorites.
- little chunks of rock and debris in space are called meteoroids – they become meteors or shooting stars, when they fall through a planet’s atmosphere – leaving a bright trail as they are heated to glow by the friction of the atmosphere.
Geminid meteor in California, USA.
- meteorites are small – less than about 1,000 tonnes, solid objects from space that have impacted the surface of a planet or moon.
- the largest known meteorite weighs more than 60 tonnes and is still lying where it fells on the farm of the same name, not far from Grootfontein,
in the Otjozondjupa Region of Namibia, Africa.
This photo shows a group of German geologists
at the Hoba Falls site in 1929.
The Hoba Fall site today, it has been uncovered but,
because of its large mass, has never been moved from where it fell.
- discovered in Greenland by the famous explorer Robert Peary in 1897 – the largest meteorite on public display weight 34 tonnes; nicknamed `Ahnighito` – Peary sold the pieces for $40,000 to the American Museum of Natural History in New York City where they are still on display.
Ahnighito – Robert Peary
- meteorites found on Earth can be divided into three main categories – popularly known as irons, stones and stony-irons.
- irons, which used to be called siderites – are composed almost entirely of the metals iron and nickel (or alloy of the two) and their found outer surface is often covered with rust.
- stones, which used to be called aerolites – are composed of silicate minerals such as pyroxene, olivine and feldspar together with a small amount of nickel or iron.
- two sub types of stony meteorites – chondrules which often have rounded appearance and a structure made up of tiny rock spheres known as chondrules and chondrites, which usually have a jagged appearance and do not contain chondrules.
- stony-irons which used to be called siderolites – are composed of silicate minerals and nickel-iron in roughly equal proportions. (Stony-irons are very rare and only about 4% of meteorites fall in this category.
- Tektites are small, rounded objects – made of silica glass;previously thought to be meteorites, it is now accepted that tektites are produced by the impact of as asteroid striking Earth.
Best places to find meteorites
- best places to find meteorites are Antarctica because there has been so little human activity there!
The most abundant meteorites found in Antarctica are called chondrites.
They are some of the oldest objects known in the solar system.
This is a stony meteorite that has not been modified,
by either melting or differentiation of the parent body.
They are formed when various types of dust and small grains
in the early Solar System accreted to form primitive asteroids.