| A | B |
|---|
| Sphere | A round, three-dimensional object |
| Axis | imaginary verticle line around which an object spins |
| Rotation | Spinning of an object on its axis |
| Ellipse | elongated, closed curve |
| 23.5 degrees | angle which the Earth's axis is tilted |
| Equinox | when the Sun is directly above the Earth's equator |
| March 20 or 21; September 22 or 23 | Equinox |
| Solistice | day when the Sun reaches its greatest distance north or south of the equator |
| June 21 or 22; December 21 or 22 | Solsitice |
| Vernal Equinox | March 20 or 21 |
| Autumnal Equinox | September 22 or 23 |
| Summer Solstice | June 21 or 22 |
| Winter Solstice | December 21 or 22 |
| Moon Phases | different forms that the Moon takes in its appearance from the Earth |
| New Moon | lighted half of the Moon is facing the Sun, and the dark side is facing the Earth |
| Waxing | illuminated half the the Moon can be seen more each night |
| Waning | illuminated half of the Moon can be seen less each night |
| Full moon | all of the Moon's surface facing the Earth reflects light |
| Solar Eclipse | Moon's shadow is cast on the Earth; Moon is between Earth and Sun |
| Lunar Eclipse | Earth's shadow is cast on the Moon; Earth is between the Sun and Moon |
| Umbra | darkest part of the shadow during an eclipse |
| Penumbra | lighter part of the shadow during an eclipse |
| Maria | dark, flat regions on the Moon |
| Impact basin | depression left behind by an object striking the Moon |
