I one looks carefully at moon pictures one can sometimes see very fine radial lines especially from the poles.
These are obvious in the superb moon picture by Pao above!
This has fascinated me and left. E perplexed as I wondered whether this was something real and reproducible or an artifact of photography. Today I finally found a discussion in Wikipedia and other sources.
Understanding Fine Radial Longitudinal Lines on the Moon
What Are Radial Longitudinal Lines?
Radial longitudinal lines on the Moon are fine, linear features that appear to extend outward from the lunar poles. These lines are often visible in photographs taken from various angles and distances. They can be attributed to several geological and physical processes.
Causes of Radial Lines
- Impact Cratering: The Moon's surface is heavily cratered due to impacts from asteroids and comets. These impacts can create radial patterns, especially around larger craters, where ejecta is thrown outwards.
- Lunar Libration: The Moon exhibits a phenomenon called libration, which allows observers on Earth to see slightly different hemispheres at different times. This can affect how features appear in photographs, making lines seem more pronounced.
- Geological Features: The Moon's surface has various geological formations, including rilles and grooves, which can create linear patterns. These features may be the result of volcanic activity or tectonic processes.
Observational Factors
- Lighting Conditions: The angle of sunlight can enhance the visibility of these lines. Shadows cast by the lunar terrain can make them appear more distinct in photographs.
- Resolution of Images: Higher resolution images can reveal finer details, including these radial lines, which may not be visible in lower-quality images.
Conclusion
The fine radial longitudinal lines seen in lunar photographs are a combination of impact cratering, geological features, and observational factors like lighting and image resolution. Understanding these elements helps in interpreting the Moon's complex surface.
Wikipedia