| A | B |
|---|
| maria | smooth, dark areas of the moon's surface |
| craters | bowl shaped depressions caused by meteorite impact |
| umbra | dark, cone-shaped part of the shadow |
| penumbra | lighter part of the shadow |
| perigee | the point when the moon is closest to the Earth |
| apogee | the point when the moon is farthest away from the Earth |
| spring tides | tides with the greatest difference in tidal rang--occur during full and new moons |
| neap tides | tides with the least difference in tidal range--occur during 1st and 3rd quarter moons |
| waxing | light part of the moon getting larger |
| waning | light part of the moon getting smaller |
| length of the moon's rotation | 27.3 days |
| length of the moon's revolution | 27.3 days |
| length of a lunar month | 29.5 days |
| tides | daily changes in the Earth's oceans caused by the pull of the moon's gravity |
| length between one high tide and the next low tide | 6 hours and 12.5 minutes |
| tidal range | the difference in height between high tide and low tide |
| flood tide | incoming or rising tide |
| ebb tide | outgoing or water moving away from the shoreline |
| comets | balls of dust, gas, and ice that orbit the sun in highly elliptical orbits |
| quarter moon phase | when 1/2 of the moon is lit up |
