| A | B |
|---|
| 29.5 days | The period of the moon's orbit around the earth |
| 365.25 days | The period of the earth's revolution around the sun |
| The closest approach of a planet to the sun | The point in a planet's orbit when it moves most rapidly |
| 180 degrees | The angle between the sun and moon (when viewed from earth) that results in a full moon |
| 90 degrees | The angle between sun and moon (as measured from Earth) that results in a "half" moon |
| Mars | The 4th planet from the sun (Earth is the 3rd) |
| Venus | The second planet from the sun (Earth is the 3rd) |
| Tangential velocity | The motion which carries a satellite (such as the moon) AROUND the earth |
| Radial velocity | The type of motion that would move a rocketship TOWARDS or AWAY FROM the earth. |
| The sun | The largest object in our solar system |
