Simply put, an asteroid is a body of rock or metal, of any size orbiting the sun. The largest known asteroid is Ceres, the largest member of the asteroid belt and the smallest known dwarf planet (Pluto is a dwarf planet) after when in 2006, the International Astronomical Union, formalized their definition of a planet. This then, begs the question, “what is the difference between a planet, a planetoid and an asteroid? If you are a chunk of rock applying for planet status; you need to have sufficient mass to orbit the sun in a nearly circular fashion, and have cleared your orbit of any other celestial bodies – get beefy and take out the trash as it were. Dwarf planet, planetoid, asteroid or minor planet were terms that were used interchangeably until 2006 when the IAU again stepped in and created guidelines for a specific classification system: if you didn’t meet the onerous requirements to officially become a planet, you could be labeled a dwarf planet as your consolation prize – you need only to have an ellipsoid orbit around the sun. Thus, Ceres is a dwarf planet, but still classified by most in the know to be an asteroid.
A meteor is the streak of light that an asteroid, or any other space debris creates as it collides with our atmosphere; an object in in transition. You can’t pick up a meteor – it is like a rainbow, an effect created by a phenomenon. If you are lucky enough to pick up a space rock that your species has not been rendered extinct by, you have in your hands a meteorite. To summarize, an asteroid is still outside Earth’s orbit; it becomes a meteor as it collides and passes through the Earth’s orbit and a meteorite is the actual matter left at the end.