| A | B |
|---|
| digit | symbol used to write numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 |
| period | a three-digit group of numbers, seperated from other groups by a comma |
| elliptical | oval-shaped, like a flattened circle |
| model | a representation of how something looks or works |
| asteroid | a rocky object that revolves around the sun |
| meteoroid | a small piece of rock or metal that travels in space around the sun |
| meteor | a bright streak of light that passes throught Earth's atmosphere |
| comet | a ball of ice, dust, and gases that travels through space and orbits the sun |
| meteorite | a piece of a meteoroid that lands on Earth after passing throught the atmosphere |
| light year | the distance light travels in one year |
| constellation | stars that appear to be in groups when viewed from Earth |
| galaxy | a group of billions of stars, dust, and gases in space held together by gravity |
| spectroscope | an instrument that seperates light into a pattern of lines of different colors |
| refraction | the bending of light as it passes from one material to another; a way to gather and focus light |
| reflection | the bouncing of light off a surface; a way to gather and focus light |
