Final answer:
The Moon's phases are ranked from brightest to dimmest as follows: full moon, waning gibbous, third quarter, waning crescent, and new moon.
Step-by-step explanation:
The brightness of the Moon's phases varies according to the amount of illumination it receives from the Sun, which is then reflected towards Earth. The ranking from the brightest to the dimmest phase would be:
- Full Moon - opposite the Sun, completely illuminated, rises at sunset and sets at sunrise.
- Waning Gibbous - less of the Moon is illuminated as it moves from full to third quarter.
- Third Quarter - half of the visible side of the Moon is dark, it rises around midnight and sets around noon.
- Waning Crescent - a smaller sliver of the moon is illuminated as it approaches the new phase.
- New Moon - not visible as the side that faces Earth is not illuminated at all, it's roughly in the same direction as the Sun.
Thus, the full moon, being completely illuminated, is the brightest, and the new moon is the dimmest since it is not illuminated from our perspective at all.