| A | B |
|---|
| rotation | when an object spins on its axis one complete turn (i.e. the moon takes 28 days to make one complete rotation) |
| revolution | when an object makes one complete orbit around another (i.e. the moon takes 27.3 days to revolve around the earth |
| sidereal period | the time it takes the moon to travel around the earth (one revolution) |
| synodic period | the time between full moons (29.53) |
| phase | the different stages in the appearance of the moon |
| illluminated | lit up by the sun |
| terminator | the line that is formed between the edge of the illuminated portion of the moon's surface and the dark portion |
| umbra | conical shadow of a celestial body ( the moon or the earth) that excludes all light from the sun |
| penumbra | area around the umbra that is a partial shadow |
| new moon | the moon has 0% of its surface illuminated; the moon is between the earth and the sun |
| waxing crescent | the moon has 1-49% of its surface illumintated; illuminated surface of the moon is increasing |
| first quarter | the moon has 50% of its surface illuminated |
| waxing gibbous | the moon has 51-99% of its surface illuminated; illuminated surface of the moon is increased |
| full moon | the moon has 100% of its surface illuminated; the earth is between the moon and the sun |
| waning gibbous | the moon has 51-99% of its surface illuminated; illuminated surface of the moon is decreasing |
| third (or last) quarter | the moon has 50% of its surface illuminated |
| waning crescent | the the moon has 1-49% of its surface illuminated; illuminated surface of the moon is decreasing |
| lunar eclipse | the earth is directly between the moon and the sun and the shadow of the earth passes across the face of the moon |
| solar eclipse | the moon is between the earth and the sun and the shadow of the moon passes across the face of the earth |
