Lab #2. Observing the Sky
Lunar Illumination
Each time that you observe the Moon, estimate its fractional illumination by comparison with the images shown below. If you observe the Moon in a phase which lies in between two of these images, interpolate between the listed fractional illuminations (choose a value that lies between them) to determine a value which matches your observed phase.
 |  |  |  |  |
| 0% | 2% | 6% | 13% | 22% |
 |  |  |  |  |
| 33% | 44% | 55% | 65% | 75% |
 |  |  |  |  |
| 83% | 90% | 95% | 98% | 100% |
 |  |  |  |  |
| 99% | 97% | 93% | 88% | 81% |
 |  |  |  |  |
| 73% | 64% | 54% | 44% | 34% |
 |  |  |  |  |
| 24% | 15% | 8% | 3% | 0% |