Everyone typically takes joy from the unexpected sighting of a shooting star; however, not everyone knows exactly what they are seeing. A “shooting” or “falling” star is actually a phenomenon where a meteoroid (a particle or small piece of stony or iron matter) enters Earth’s atmosphere creating a streak or trail of light across the sky. The vaporization of the meteoroid as it enters our atmosphere causes friction which we see from the surface as a stunning trail of brightly colored light, streaking across the night sky. Although most meteors burn up upon entering the atmosphere, the ones that make it all the way to the surface are called meteorites. By studying these meteorites we have learned that there are three types of meteors: Stony, Iron and a combination of the two called Stony-Iron.
The most common type of meteor is made of rocks and dust and is refereed to as a stony meteor. These meteors are made up primarily of minerals which have melted and melded together with other minerals to form solid rocks. There are three subclasses of stony meteors: chondrites, carbonaceous chondrites, and achondrites. Chondrites are made up of materials similar to the mantles and crusts of Earth or other planets, and are thought to be among the oldest rocks in the solar system. Carbonaceous chondrites are highly rare and contain elemental carbon which is one of the basic building blocks of life on Earth. Least common of the stony type are the achondrites. These are stony meteors without chondrules (the melted minerals which form chondrite and carbonaceous chondrite meteors). The majority of these are believed to be basalt lavas which originated from the surface of Mars.
The next most common type of meteor is made up primarily of an iron-nickel alloy resembling Earth’s outer core. These typically create the meteorites with the largest mass such as the 60 ton iron meteorite discovered around 1920 in Hoba, Namibia. The Hoba meteorite, as it’s known, is the largest intact meteorite on Earth today and remains at the farm where it was originally discovered since it’s obviously far too large to move to a museum.
Finally, we come to the third and least common type of meteor, the stony-iron. As the name suggests these are made up of both the materials contained in a stony meteor and the materials contained in an iron meteor. Many scientists compare this to the material which would be found where a planet’s core and mantle meet. According to meteorite fall statistics, only 1% of meteor falls are of the stony-iron classification (Gale Encyclopedia of Science).
Sources:
Gale Encyclopedia of Science. Eds. K. Lee Lerner and Brenda Lerner. Vol. 4. 3rd ed. p2535-2539. From General OneFile. Retrieved from http://find.galegroup.com.ezproxy.apollolibrary.com
Meteors and Meteorites. (2011). AustralianMuseum.net.au. Retrieved from http://australianmuseum.net.au/Meteors-and-Meteorites
Meteor and Meteoroid. (2011). Encyclopedia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/378109/meteor
