| A | B |
|---|
| 23.5 degrees | tilt of the Earth on its axis |
| Orbit | A path that a planet follows |
| rotation | spinning on an axis |
| revolution | the movement of one object around another |
| seasons | occurs because of the earth's tilt |
| equinox | equal nights and day hours |
| law of universal gravitation | every object in the universe attracts every other object |
| new moon | a moon phase that cannot be seen |
| umbra | Here you can see a total ecllipse |
| astronomy | study of the moon, stars and other objects |
| solstices | when the sun is the farthest N or S of the equator |
| equal nights | equinox |
| mass | the amount of matter |
| inertia | tendency of an object to resist change in motion |
| orbital motion | needs 2 factors: inertia and gravity |
| waxing phase of the moon | just keeps growing |
| waning phase of th moon | just keeps getting smaller |
| gibbous | more than 1/2 the moon is sunlit |
| crescent | less than 1/2 the moon is sunlit |
| spring tide | sun and moon are in alignment |
| high tide | caused by the moon's gravity |
| solar eclipses | occurs only during the daytime |
| lunar eclipses | occurs only at nighttime |
| blue moon | 2nd Full Moon in a month |
| June 21 | Summer Solstices in Northern hemisphere |
| December 21 | Winter Solstices in Northern hemisphere |
