| Term | Definition |
| Rotation | the spin of an object in space. (Note:Period of rotation is the amount of time it takes for an object to make one complete rotation.) |
| revolution | the elliptical motion of a body as it travels around another more massive body in space. (Note: Period of revolution i the amount of time it takes for one object to revolve around another object.) |
| orbit | the elliptical path of an object takes in space while revolving around another object |
| gravity | attracting force due to mass or rotation |
| atmosphere | mixture of gases that surrounds a planet |
| sun | a medium sized star; the center of our solar system |
| planet | body that orbits around the sun or a star and does not produce is own light |
| terrestrial planet | a small, dense, rocky planet similar to earth |
| gas giant | a large, gaseous planet of the outer solar system with no known solid surface. (Outer planets) |
| natural satellite | smaller body that orbits around a larger body |
| moon | a natural satellite of planet. (Note: satellites are natural or artifical bodies that revolve around more massive bodies such as planets_ |
| artifical satellite | any human made object placed in orbit around a body in space |
| comet | a small body of ice, rock, and cosmic dust loosely paced together |
| asteroid | a small, rocky body revolves around th sun |
| meteoriod | a very small, rocky body found in space (HINT: min asteroid) |
| meteorite | a meteoriod that reaches Earth's surface without burning up completely (HINT: it takes the "right" path to earth) |
| meteor | a bright streak of light caused when a meteriod or comet dist burns up in the atmosphere (NOTE many people call this a shooting star but its not) |
| thrust | the force that accelerates a rocket |
| orbital velocity | the speed and direction a rocket must have in order to orbit earth |
| escape velocity | the speed and direction a rocket must have in order to completely break away from a planet's gravitaional pull |
| centripetal force | the force that causes an object to follow a curved path |
