| 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 |
| phase | one of the different apparent shapes of the moon as seen from Earth |
| eclipse | the partial or total blocking of one object in space by another |
| solar eclipse | moon blocks our view of the sun by coming directly between the sun and Earth |
| umbra | darkest part of the moon's shadow |
| penumbra | part of the moon's shadow that surrounds the darkest part |
| lunar eclipse | Earth blocks sunlight from reaching the moon when it moves directly between the sun and the moon |
| tide | rise and fall of ocean water |
| neap tide | time when the difference between high tide and low tide is least |
| spring tide | time when there is the greatest difference between high and low tide |
| telescope | instrument used to see distant objects |
| maria | dark flat areas on the moon |
| craters | large round pits on the moon's surface |
| meteoroids | chunks of dust or rock from space |
