A New View on the Solar Wind Interaction with the Moon
Bhardwaj et al. Geosci. Lett. (2015) 2:10 DOI 10.1186/s40562-015-0027-y REVIEW Open Access A new view on the solar wind interaction with the Moon Anil Bhardwaj1* , M B Dhanya1, Abhinaw Alok1, Stas Barabash2, Martin Wieser2, Yoshifumi Futaana2, Peter Wurz3, Audrey Vorburger4, Mats Holmström2, Charles Lue2, Yuki Harada5 and Kazushi Asamura6 Abstract Characterised by a surface bound exosphere and localised crustal magnetic fields, the Moon was considered as a passive object when solar wind interacts with it. However, the neutral particle and plasma measurements around the Moon by recent dedicated lunar missions, such as Chandrayaan-1, Kaguya, Chang’E-1, LRO, and ARTEMIS, as well as IBEX have revealed a variety of phenomena around the Moon which results from the interaction with solar wind, such as backscattering of solar wind protons as energetic neutral atoms (ENA) from lunar surface, sputtering of atoms from the lunar surface, formation of a “mini-magnetosphere” around lunar magnetic anomaly regions, as well as several plasma populations around the Moon, including solar wind protons scattered from the lunar surface, from the mag- netic anomalies, pick-up ions, protons in lunar wake and more. This paper provides a review of these recent findings and presents the interaction of solar wind with the Moon in a new perspective. Keywords: Moon, Solar wind, ENAs, Plasma, Mini-magnetosphere, Lunar wake, Pickup ions, SARA, CENA, SWIM, Chandrayaan-1, Kaguya, Chang’E-1, ARTEMIS, IBEX Introduction charge state and ≤28 % as hydrogen energetic neutral The Moon is a regolith covered planetary object char- atoms (ENAs), existence of “mini-magnetosphere” at the acterised by a surface-bound exosphere (Killen and Ip lunar surface, reflection of solar wind protons from lunar 1999; Stern 1999; Sridharan et al.
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