A meteorite is a small object that originates in outer space, enters the Earth’s atmosphere, and survives impact. Most meteorites come from larger space objects such as meteroids but they can also be formed when an asteroid impacts and throws of meteorite fragments.
Once an object like meteorites enter the Earth’s atmosphere, the pressure, speed, and density of the atmosphere cause friction as the meteorite speeds through the air. This causes immense heat build up and an emission of light…that’s why people will sometimes see “fireballs” hurtling through the day or night sky. You may have heard these referred to as a meteor or “shooting star” and “falling star” as you were growing up or seen closely through a telescope.
However, to get darn right specific (correct) a meteorite is any outer space object or fragment that collides and survives with any celestial body. So, by definition, there are meteorites on the Moon, Mars and any other planet…yada, yada, yada.
In meteor hunting and collecting lingo, any meteorite that is observed entering the atmosphere and then chased down for recovery are referred to as a meteorite “fall”. So, a “witnessed fall” is one that is seen as it happens. Make sense?
Terms to Know:
Bolide (noun) and per Wikipedia:
A bolide (French via Latin from the Greek βολίς bolís, “missile”) is an extremely bright meteor, especially one that explodes in the atmosphere. In astronomy, it refers to a fireball approximately as bright as the full moon, and it is generally considered a synonym of a fireball. In geology, a bolide is a very large impactor.
One definition describes a bolide as a fireball reaching an apparent magnitude of −14 or brighter – more than twice as bright as the full moon. Another definition describes a bolide as any generic large crater-forming impacting body whose composition (for example, whether it is a rocky or metallic asteroid, or an icy comet) is unknown
Traditional Categories of Meteorites
- Mostly rock material made of silicate minerals
- Mostly metallic materials such as iron and nickel.
- Comprised of both characteristics.
Contemporary classification of meteorites goes much deeper than just simple composition, though, and includes such things as structure, chemical base, isotopic mineralization (WTH) and mineralogy.