The “Stars” of Moon
There are over 8,600 named craters on the moon. Many named crater features have one or more “satellite” features, usually other craters. These features are given the name of the central crater with a unique capital letter added to the end to distinguish it from the others. For example, the crater called Copernicus has 12 satellite features. These features are named Copernicus A, Copernicus B, and so on (see map plate Reinhold E-14).
This is slightly atypical in that places on Mars, Mercury, and Venus do not follow this naming convention. Each named feature is unique in its own right - however with Moon’s many features reusing names helps make place orientation more decipherable.
Fig 1. Copernicus Crater and satellite features
Fig 2. Illustration of radiating satellite features southwest of Mare Crisium
During our mapping of the lunar surface, the team decided to remove the prefix from all satellite features, instead of labeling features by their distinguishing capital letter. Cartographically this reduced the amount of label “clutter” on the maps, allowing users to see more of the underlying topography. This created a cacophony of floating letter labels that were difficult to decipher. It was decided that we should connect all related satellite features with their central feature with a series of lines, creating “hubs” or “starbursts.” This focuses the attention of the map reader to broader areas, with fewer labels, facilitating a full view of the underlying landscape.
Fig 3. “Starbursts” of lunar place names created by connecting named satellite features to their central feature
Interestingly, when one zooms out to the full extent of the Moon you see a pattern emerge of clusters of labeled features. The density of these clusters is, as it happens to be, on the bright side of the Moon, that part which is visible to observers from Earth. Despite more features existing on the dark side of the Moon. It’s a great illustration of how we as humans develop our understanding of place. We prioritize the naming of places we can see and visualize, further demonstrating the importance of maps as tools of exploration. If you can’t visit or visualize a place, it will be less likely to have a name. If the place doesn’t have a name, it is less likely to be further investigated. By mapping the surface of the Moon, we hope to inspire others to explore our nearest celestial neighbor.
Fig 4. “Starbursts” of lunar place names overlaying lunar topography