ASTRO 101 Lecture Notes - Lecture 12: Kuiper Belt, Impact Crater, Oort Cloud
Document Summary
However, precise definitions are still debated, and boundaries between catego- ries are sometimes fuzzy. Small pieces of dust or rock continually enter earth"s atmosphere. Technically, a meteor is the flash of light that we see as a bit of rock burns up at high speed in the atmosphere, and most meteor particles burn up completely. In the relatively rare cases where the particle is large enough to survive and reach the ground, the rock that we find is called a meteorite. Asteroids come in a wide range of sizes and shapes, though small ones are far more common. All are rocky in composition, but those at greater distances from the sun contain more carbon compounds and water. Despite their enormous numbers, the total mass of all asteroids combined is less than that of our moon. Primitive meteorites are essentially unchanged since the birth of the solar system and tell us about the material that accreted to make asteroids and planets.
