Reiner Gamma is a prominent nearside landmark hundreds of kilometers long (centered at 300.972°E, 7.409°N). The distinctiveness of this feature, in part, arises from the sharp albedo contrast between the Reiner Gamma swirl (bright) and the surrounding mare volcanic plains (dark). This meandering bright formation is reminiscent of swirling brush strokes from an artist's paintbrush (see WAC context image below). However, does the brightness of the lunar swirl result from the addition of bright material, or might it result from the lack of adding dark material, or something else? Scientists have long studied the formation mechanisms of the bright swirls (Reiner Gamma is one of several), which have thus far only been recognized on the Moon. Most swirls occur in locations with localized magnetic fields, suggesting a connection between swirl formation and magnetic fields.
While magnetic fields are uncommon on the Moon, much of the surface experienced significant tectonic activity, resulting in flexing and faulting of the surface. In fact, several wrinkle ridges are prominent throughout the Reiner Gamma region, including the one shown in today's Featured Image. However, further study is needed to determine the relative ages of the faulting and the albedo anomaly at Reiner Gamma. Specifically, did the compressional stresses associated with the formation of wrinkle ridges deform the albedo anomaly, or is the albedo anomaly draped over pre-existing faults and folds?
These questions (and more) about Reiner Gamma still remain unanswered. Future high resolution study of both the composition and structure of Reiner Gamma is yet needed. However, the swirls are likely formed through a surface process that does not deposit or remove large volumes of additional materials. The Reiner Gamma formation or other lunar swirls remain excellent targets for future exploration!
Read more about Reiner Gamma and other swirls and how they might have formed here:
The Reiner Gamma Constellation Region of Interest
Lunar Swirls at the Mare Ingenii Constellation Region of Interest
Explore the full color shade relief map below!
Download the full NAC DTM and color shaded relief map here:
LROC NAC DTM REINER4
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