| A | B |
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| Astronomy | The study of the moon, stars, and other objects in space. |
| axis | An imaginary line that passes through Earth's center and the North and South poles, about which Earth rotates. |
| Rotation | The spinning motion of a planet about its axis. |
| Revolution | The movement of an object around another object. |
| Orbit | The path of an object as it revolves around another object in space. |
| Latitude | A measurement of distance from the equator, expressed in degrees north or south. |
| Solstice | The two days of the year on which the noon sun is directly overhead at either 23.5 degrees South or 23.5 degrees North. |
| Equinox | The two days of the year on which neither hemisphere is tilted toward or away from the sun. |
| Vernal equinox | The day of the year that marks the beginning of spring in the Northern Hemisphere. |
| Autumnal equinox | The day of the year that marks the beginning of fall in the Northern Hemisphere. |
| Phase | One of the different shapes of the moon as seen from Earth. |
| Eclipse | The partial or total blocking of one object by another. |
| Solar eclipse | The blocking of sunlight to Earth that occurs when the moon is between the sun and Earth. |
| Umbra | The darkest part of a shadow. |
| Penumbra | The part of a shadow surrounding the darkest part. |
| Lunar eclipse | The blocking of sunlight to the moon that occurs when Earth is directly between the sun and moon. |
| Tide | The rise and fall of the level of water in the ocean. |
| Gravity | The attractive force between two objects; its magnitude depends on their masses and the distance between them. |
| Spring tide | A tide with the greatest difference between low and high tides. |
| Neap tide | A tide with the least difference between low and high tides. |
| Satellite | Any object that revolves around another object in space. |
| Geosynchronous orbit | The orbit of a satellite that revolves around Earth at the same rate that Earth rotates. |
| Telescope | A device built to study distant objects by making them appear closer. |
| crater | A round pit on the moon's surface. |
| Maria | Dark, flat regions on the moon's surface. |
