Here's why:

* New Moon: The moon is positioned between the Earth and the Sun. Its sunlit side faces away from us, making it completely invisible from Earth.

* Other Phases: As the moon orbits the Earth, we see increasing amounts of its sunlit side, leading to the waxing phases (crescent, first quarter, gibbous). During the waning phases (gibbous, last quarter, crescent), the sunlit portion gradually shrinks.

So, while other phases may appear darker than a full moon due to their smaller illuminated area, the New Moon is the darkest because we cannot see it at all.