| A | B |
|---|
| Astronomy | Study of the moon, stars, and other objects in space. |
| Rotation | Spinning motion of a planet on its axis. |
| Revolution | Movement of an object around another object. |
| Axis | Imaginary line that passes through Earth's center and the north and south poles. |
| Orbit | Path of an object as it revolves around another object. |
| Solstice | Time of the year when one hemisphere is pointed directly towards the sun. Winter solstice: December 21 (longest nighttime); Summer Solstice - June 21 (longest daytime) |
| Phase | One of the different shapes of the moon as seen from Earth. |
| Lunar Eclipse | Blocking of sunlight to the moon that occurs when Earth is directly between the sun and moon. (Sun, Earth, Moon) |
| Solar Eclipse | Blocking of sunlight to Earth that occurs when the moon is directly between the sun and Earth. (Sun, Moon, Earth) |
| Tide | Rise and fall of the water level in the ocean. |
| Gravity | Attractive force between two objects. Magnitude depends on the mass and distance between objects. |
| Spring Tide | Tide with the greatest difference between low and high tides. |
| Neap Tide | Tide with the least difference between low and high tides. |
| Satellite | Any object that revolves around another object in space. |
| Geosynchronous Orbit | Orbit of a satellite that revolves around Earth at the same rate that Earth rotates. |
| Crater | Round pit on the moon's surface. |
| Maria | Dark, flat regions on the moon's surface. |
| Telescope | Device built to study objects by making them appear closer. |
| Intertidal Zone | Region of land between the high and low tides. |
| Equinox | Time of the year when neither the northern or southern hemisphere is pointed directly towards the sun. Daytime & nightime are equal. Vernal Equinox - March 21; Autumnal Equinox - September 21 |
