Reiner Gamma
Bright lunar swirl on Oceanus Procellarum; origin unknown, linked to magnetic anomaly.
Last refreshed: 7 April 2026
Why does Reiner Gamma glow brighter than the lunar surface around it?
Latest on Reiner Gamma
- Why is Reiner Gamma so bright on the Moon?
- Reiner Gamma is a lunar swirl associated with a magnetic anomaly. The leading hypothesis is that the anomaly deflects solar wind, reducing space weathering and preserving brighter albedo.
- Can you see Reiner Gamma from Earth?
- Yes. It sits on the near side of the Moon in western Oceanus Procellarum and is visible through a telescope from Earth.
Background
Reiner Gamma is a bright, tadpole-shaped swirl on the western edge of Oceanus Procellarum, on the near side of the Moon. It was observed by the Artemis II crew during the Day 6 lunar flyby on 6 April 2026, as part of the six-hour photography programme. Its unusual brightness stands out against the darker mare basalt surrounding it, making it one of the most visually distinctive features on the near side.
Lunar swirls are among the Moon's least understood surface phenomena. Reiner Gamma is associated with a localised magnetic anomaly — an unusually strong magnetic field for a body with no global magnetic field. The leading hypothesis links the swirl pattern to solar wind deflection by this anomaly, which shields the surface from space weathering and preserves brighter albedo. No impactor origin has been confirmed.
The feature has been a scientific target for several lunar orbiting missions. Its proximity to the near-side limb and visibility from Earth make it one of the more accessible puzzles in lunar geology. Artemis II crew observations, combined with orbital imagery, may contribute to post-mission analysis.