| A | B |
|---|
| astronomy | study of objects in space |
| axis | imaginary line around which an object rotates |
| rotation | spinning on axis |
| revolution | movement of one object around another |
| orbit | path an object follows when revolving |
| solstice | longest and shortest days of the year |
| equinox | days when hours of sunlight equal hours of nighttime |
| force | push or pull |
| gravity | attraction of one object to another |
| law of universal gravitation | all objects in the universe attract each other |
| mass | amount of matter in an object |
| weight | force of gravity on an object |
| inertia | tendency of an object to resist change in motion |
| Newton's first law of motion | an object at rest remains at rest, an object in motion remains in motion unless acted on by an oustide force |
