Reiner Gamma

Reiner gamma
Lunar Reconnaissance Orbiter Wide Angle Camera image of Reiner Gamma.
Coordinates7°30′N 59°00′W / 7.5°N 59.0°W / 7.5; -59.0
Diameter73.44 km (45.63 mi)
EponymReiner crater

Reiner Gamma (γ) is a geographical feature of the Moon known as a lunar swirl. It is one of the most visible lunar swirls from Earth, visible from most telescopes. It was originally thought to be a lunar highland, but scientists eventually realized that it cast no shadow on the moon. In contrast to many ray systems, it remains prominent even under a low Sun.

Name

In early lunar maps by Francesco Maria Grimaldi, this feature was incorrectly identified as a crater. His colleague Giovanni Riccioli then named it Galilaeus, after Galileo Galilei. The name was later transferred northwest to the current crater Galilaei. The feature is now named after Italian astronomer and mathematician Vincentio Reinieri (unknown–1648). Its designation was officially adopted by the International Astronomical Union in 1935.

Description

Reiner Gamma is located on the Oceanus Procellarum, west of the crater Reiner. Its center is located at selenographic coordinates 7°30′N 59°00′W / 7.5°N 59.0°W / 7.5; -59.0. It lies across a wrinkle ridge and has an overall length of about 70 kilometres. The feature has a higher albedo than the relatively dark mare surface, with a diffuse appearance and a distinctive swirling, concentric oval shape. Related albedo features continue across the surface to the east and southwest, forming loop-like patterns over the mare.

The central feature of Reiner Gamma resembles the dipolar formation created by iron filings on a surface with a bar magnet on the underside. Low-orbiting spacecraft have observed a relatively strong magnetic field associated with each of these albedo markings. Some have speculated that this magnetic field and the patterns were created by cometary impacts. However the true cause remains uncertain.

Reiner Gamma's magnetic field strength is approximately 15 nT, measured from an altitude of 28 km. This is one of the strongest localized magnetic anomalies on the Moon. The surface field strength of this feature is sufficient to form a mini-magnetosphere that spans 360 km at the surface, forming a 300 km thick region of enhanced plasma where the solar wind flows around the field. As the particles in the solar wind are known to darken the lunar surface, the magnetic field at this site may account for the survival of this albedo feature.

Origin

The origin of Reiner Gamma—like other lunar swirls—is not completely understood. It is associated with a localized magnetic field, but not with any particular irregularities in the surface. Similar features have been discovered in Mare Ingenii and Mare Marginis by orbiting spacecraft. The feature on Mare Ingenii is located at the lunar opposite point from the center of Mare Imbrium. Likewise the feature on Mare Marginis is opposite the midpoint of Mare Orientale. Hence, one hypothesis is that the feature resulted from seismic energies generated by the impacts that created these maria. However, no such lunar mare formation is on the opposite side of the Moon from Reiner Gamma. Instead, it is oriented approximately radially to the Imbrian basin and so may be related to magnetized ejecta from that source.

Exploration

NASA and Intuitive Machines plan to land the IM-3 mission in the Reiner Gamma region in 2027. The mission's Lunar Vertex payload is designed to study the lunar swirl environment.

References

  1. 1 2 3 "Reiner Gamma". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program. Retrieved 2026-10-04.
  2. ↑ "Lunar Swirls". Retrieved 18 April 2017.
  3. ↑ "Bubble Bubble - Swirl and Trouble". Retrieved 18 April 2017.
  4. 1 2 3 Grego, Peter (2005). The Moon and How to Observe It. Astronomers' Observing Guides Series. London: Springer-Verlag. p. 169. ISBN 1-85233-748-6.
  5. ↑ "The Curious Case of Galileo's Tiny Moon Crater". NASA Space News. May 23, 2024. Retrieved 2026-10-04.
  6. ↑ King, Bob (May 22, 2024). "Why Did Galileo Get Such a Puny Crater?". Sky & Telescope. Retrieved 2026-10-04.
  7. ↑ Richmond, N.C.; et al. (2003). "Correlation of a Strong Lunar Magnetic Anomaly with a High-Albedo Region of the Descartes Mountains". Geophysical Research Letters. 30 (7): 48. Bibcode:2003GeoRL..30.1395R. doi:10.1029/2003GL016938. hdl:10150/623384. S2CID 128822762.
  8. ↑ Wieser, Martin; et al. (March 2010). "First observation of a mini-magnetosphere above a lunar magnetic anomaly using energetic neutral atoms". Geophysical Research Letters. 37 (5): L05103. arXiv:1011.4442. Bibcode:2010GeoRL..37.5103W. doi:10.1029/2009GL041721. S2CID 117346419.
  9. ↑ L. L. Hood; C. R. Williams (1989). "The Lunar Swirls - Distribution and Possible Origins". Proceedings 19th Lunar and Planetary Science Conference. Cambridge University Press/Lunar and Planetary Institute. Bibcode:1989LPSC...19...99H.
  10. ↑ Huddleston, Marvin (October 29, 2009). "Lunar swirls, magnetic anomalies, and the Reiner Gamma formation". The Rambling Observer. Archived from the original on 7 December 2019. Retrieved 7 December 2019.
  11. ↑ Hood, Lon L.; et al. (June 2013). "Origin of strong lunar magnetic anomalies: Further mapping and examinations of LROC imagery in regions antipodal to young large impact basins". Journal of Geophysical Research: Planets. 118 (6): 1265–1284. Bibcode:2013JGRE..118.1265H. doi:10.1002/jgre.20078.
  12. ↑ "NASA Awards Initial Moon Base Rover and Lander Contracts". Retrieved 2026-10-28.
  13. ↑ "The Space Review: Dodging bullets and firing blanks". www.thespacereview.com. Retrieved 2026-10-28.
  14. ↑ Vines, Sarah; Ho, George; Blewett, David; Halekas, Jasper; Greenhagen, Benjamin; Anderson, Brian; Waller, Dany; Jahn, Jörg-Micha; Kollmann, Peter (2023-05-15). "Lunar Vertex: A PRISM Science Investigation of the Reiner Gamma Lunar Magnetic Anomaly and Swirl". doi:10.5194/egusphere-egu23-10526. Retrieved 2026-10-28.{{cite web}}: CS1 maint: unflagged free DOI (link)