| A | B |
|---|
| axis | imaginary line around which an object spins |
| ellipse | an elongated, closed curve |
| equinox | two times each year when the sun is above the earth's equator |
| first quarter | moon phase halfway between new moon and full moon |
| full moon | moon phase when the side facing earth is completely lighted |
| lunar eclipse | when Earth's shadow falls on the moon |
| maria | dark, flat regions of ancient lava on the moon |
| mascon | concentration of mass on the moon located under an impact basin |
| moon phase | change of appearance of the moon as it orbits |
| new moon | moon phase when the side facing Earth is completely dark |
| revolution | the orbiting of one object around another |
| rotation | the spinning of an object around its axis |
| solar eclipse | when the moon casts a shadow on part of the Earth |
| solstice | the two times each year when the sun is farthest from the equator |
| sphere | a round, three-dimensional object |
| third quarter | moon phase halfway between full moon and new moon |
| waning | when the visible lighted area of the moon grows smaller |
| waxing | when the visible lighted area of the moon grows larger |
