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Updated: Jul 12, 2026
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Summary
Voyager images reveal the Uranian lambda ring has significant brightness variations and a unique shape. These features suggest a hidden moon, but no known moon orbits at the predicted location.
Area of Science:
- Planetary Science
- Astronomy
- Ring Systems
Background:
- The Uranian lambda ring, part of Uranus's ring system, exhibits complex structures.
- Previous observations lacked the resolution to detail fine-scale variations within the ring.
Purpose of the Study:
- To analyze high-resolution Voyager images of the Uranian lambda ring.
- To investigate the ring's longitudinal brightness variations and shape.
- To determine the dynamical cause of observed ring features.
Main Methods:
- Reprocessing of archival Voyager images of Uranus.
- Photometric analysis of ring brightness variations.
- Orbital dynamics modeling to explain ring structure.
Main Results:
- The lambda ring displays significant longitudinal brightness variations, comparable to Saturn's F and Neptune's Adams rings.
- A dominant five-cycle (72-degree) periodicity and finer structures were identified.
- The ring's shape is characterized by eccentricity and a 4 km radial amplitude variation with a six-cycle (60-degree) periodicity.
Conclusions:
- The observed ring features are consistent with resonant perturbations from an undiscovered moon.
- The inferred moon's semimajor axis is 56,479 km.
- The required moon mass suggests it should have been detectable by Voyager, posing a mystery.
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