| Lunar Cycle Lab | Study Questions | Basic Celestial Phenomena |
| New | Waxing Crescent | First Quarter | Waxing Gibbous | Full |
| Waning Gibbous | Third Quarter | Waning Crescent |

That the Moon is intrinsically dark and shines by reflected light was assumed by most ancient astronomers (with some exceptions). Indeed, if the Moon were a better reflector it would shine much brighter. The intensity of the reflected light divided by the intensity of the incident light upon the Moon from the Sun (= "albedo") is only 0.07, so that 93% of the sunlight that strikes the Moon's surface is absorbed.

How much of the Moon is illuminated by the Sun?

Half of the Moon is always illuminated by the Sun (except during a lunar eclipse), though the illuminated half is not always turned toward the Earth. The far side is not the same as the dark side.

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