| A | B |
|---|
| energy transformation | gained kinetic energy is reconverted back to potential energy |
| sidereal month | one complete revolution of the moon (27 1/3 days) |
| phases of the moon | as the moon revolves it passes through a cyclic series; an observer sees varying amounts of the illuminated portion of the moon |
| synodic or lunar month | the length of time for the moon to complete the cycle from new moon to new moon (29 1/2 days) |
| spring tide | tides with the greatest range caused by the Sun's gravitation reinforcing the moon's gravitation |
| neap tides | tides with the smallest range that occur at the first and third quarter moon phases |
| umbra | total darkness |
| penumbra | partial darkness |
| lunar eclipse | when the entire moon passes into the Earth's umbra |
| total solar eclipse | when the moon is close enough so that the umbra reaches the Earth's surface |
| solar eclipse | partial eclipse seen by areas of the Earth in the penumbra |
| geocentric model | Earth-centered; explains the motion of the stars, Sun, Moon and planets as seen from Earth |
| heliocentric model | Sun-centered; explains movement Earth and other celestial objects as they revolve around the Sun |
| epicycle | smaller secondary orbit |
| terrestrial | Earth-like |
| asteroid belt | area containing most meteorites |
| meteors | shooting stars |
| fireballs | bolides; explode into fiery pieces as they fall toward Earth |
| annular eclipse | a bright ring of solar surface seen behind the dark disk of the moon |
| solar system | made up of the Sun, its nine satellite planets, moons and other celestial objects revolving around the Sun |
