What's the difference between a meteor, meteoroid, meteorite, asteroid, planetoid, planet, comet, etc.?
A wide variety of terms is used to describe planetary bodies in the Solar System:
A large rocky, metallic and/or gaseous body in orbit around a central star.
A rocky and/or metallic body or collection of bodies in orbit around the Sun that formed early in Solar System history and has changed little since that time. Can also be identified as a planetoid or minor planet.
A natural, solid object, up to 1 m (39 3/8") in size, moving in interplanetary space, not limited to asteroids or objects derived from a larger celestial body.*
A trail of light produced by a meteoroid as it passes through an atmosphere (also called a "shooting star"). Most "shooting stars" observed in the night sky actually result from dust-sized particlest, rather than large objects. However, the biggest objects that fall to Earth may result in large craters, such as Barringer Meteor Crater, on the planet's surface.
A meteoroid that was naturally transported from the celestial body on which it formed to a region beyond that body's gravitational field, and that later collided with the surface of a celestial body larger than itself, such as Earth.* A "fall" is a meteorite that was observed to fall and then collected. A "find" is a meteorite what was not observed to fall but that was recognized by distinct features.
An ice- and- rock-bearing body that travels in a highly elliptical orbit around the Sun. Gas and dust released from the comet as it nears the Sun gives a comet its characteristic tail.
Yes, however, they are extremely rare, and are not metallic. Learn more about these unusual meteorites in the achondrites section!
How old are meteorites?
Meteorites range in age. The oldest particles in a meteorite, calcium-aluminum-rich inclusions from carbonaceous chondrites, have been dated at 4.56 years old Meteorites that originate from asteroids are all ~4.5 billion years old. Meteorites that originate from the Moon range in age from 4.5 to 2.9 billion years old. Meteorites that originate from Mars range in age from 4.5 billion years old to 200 million years old.
Where and when do meteorites usually hit/occur?
Meteorites can and do hit the Earth anywhere and anytime. Click here for more information.
How do we know whether a meteorite is a new, distinct meteorite or part of an older find?
Detailed microscopic, chemical and mineralogical analyses are required to uniquely identify and classify a meteorite. Such analyses can distinguish between two meteorites that fell in a single area at different times, or can link two specimens of a single meteorite event that were found in separate locations or at separate times.