| A | B |
|---|
| rotation | The spinning motion of a planet about its axis. |
| revolutioin | The movement of an object around another object. |
| axis | An imaginary line that passes through Earth's center and the North and South ploes, about which Earth Rotates. |
| orbit | The path of an object as it revolves around another object in space. |
| 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 titled toward or away from the sun. |
| summer solstice | Around June 21, the longest day of the year in the Northern Hemisphere. |
| winter solstice | Around December 21 each year, this is the shortest day of hte year in the Northern Hemisphere. |
| vernal equinox | The day that marks the beginning of spring i the Northern Hemisphere. |
| autumnal equinox | The day of the year that marks the beginning of fall in the Northern Hemisphere. |
| eclipse | The partial or total blocking of one object by another. |
| umbra | The darkest part of a shadow. |
| penumbra | The part of a shawdow surrounding the darkest part. |
| lunar eclipse | The blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon. |
| solar eclipse | The blocking of sunlight to Earth that occurs when the moon is between the sun and Earth. |
| tide | The daily rise and fall of Earth's waters on shores. |
| satellite | Any object that revolves around another object in space. |
| telescope | A device built to study distant objects by making them appear closer. |
| geosynchronous orbit | The orbit of a satellite that revolves around Earth at the same rate that Earth rotates. |
