“Objects in the Lunar 100 are arranged from the easiest to view to the most difficult. This is more systematic than the haphazard approach that produced the Messier list. Indeed, just by knowing a feature’s Lunar 100 number, you have some idea of how easy or challenging it will be to see. For example, the Moon itself is L1, while L2 is earthshine and L3 is the light/dark dichotomy between lunar highlands and maria (“seas”).“
Planetary scientist Charles Wood’s Lunar 100 is a list of telescopic sights designed to ignite interest in the Moon and enhance understanding of its geology.
In many of these images I have chosen to use the “Auto Levels” setting in PhotoShop CS3, which seems to add “enhanced” colour to the image and brings out more contrast in the lunar materials. Although not an accurate representation of what you actually see on the Moon, it seems to me that it does help in identifying features of lunar geology – which is the whole point of the Lunar 100 after all. For example, in L18 Mare Serenitatis, the dark edges stand out significantly more in the “enhanced” picture.