| A | B |
|---|
| apogee | the farthest approach of a satellite to the Earth |
| perigee | the closest approach of a satellite to the Earth |
| tides | the rise and fall of the oceans usually occuring twice a day |
| lunar eclipse | a shadowing of the moon; occurs when the Earth lies between the sun and the moon |
| solar eclipse | a shadowing on the Earth; occurs when the moon passes between the Earth and the sun |
| ellipse | a closed curve around two fixed points (foci); the orbits of the planets are ellipses |
| moonrise | the time when the moon appears to rise near the eastern horizon |
| moonset | the time when the moon appears to set near the western horizon |
| apparent diameter | how large an object looks; depends on the size and distance from an observer |
| synodic month | the time for moon phases to repeat |
| sidereal month | the time for the moon to revolve once around the Earth |
