| Term | Definition |
|---|---|
| sphere | a round three dementional object whose surface is the same distance from its center at all points:Earth is a sphere that bulges somewhat at the equator is slightly flattened at the poles. |
| axis | imaginary vertical line that cuts through the center of the Earth and around which Earth spins. |
| rotation | spinning of Earth on its imaginary axis, which takes about 24 hours to complete and cause day and night. |
| revolution | Earth's year long elliptical orbit around the sun |
| ellipse | elongated closed curve that describes Earth's year long orbit around the sun |
| solstice | twice-yearly point at which the sun reaches its greatest distance north or south of the equator. |
| equinox | twice-yearly time each spring and fall when the sun is directly over the equator and the number of daylight and nighttime hours are equal world wide. |
| moon phase | change in appearance of the moon as viewed from the Earth, due to the relative positions of the Moon Earth and Sun |
| new moon | moon phase that occurs when the moon is between the Sun and Earth, at which cannot be seen because its lighted half is facing the Sun and its dark side id facing Earth |
| waxing | more of the illuminated half of the moon can be seen each night |
| full moon | phase that occurs when all of the moon's surface is facing Earth and reflecting light. |
| waning | describes phases that occur after a full moon as the visible lighted moon grows smaller |
| solar eclipse | occurs when the moon passes directly in between the Earth and the Sun and casts a shadow over part of Earth |
| lunar eclipse | occurs when Earths shadow falls on the moon, making the moon receive no illumination |
| maria | dark-colored relatively flat regions of the moon formed when ancient lava reached the surface and filled craters on the moons surface |
| impact basin | a hollow left on the surface of the moon caused by an object striking its surface |
