Interaction between terrestrial plasma sheet electrons and the lunar surface: SELENE (Kaguya) observations

Yuki Harada, Shinobu MacHida, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Masaki N. Nishino, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Futoshi Takahashi, Masaki Matsushima, Hisayoshi Shimizu

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13 Citations (Scopus)


Analysis of the data obtained by SELENE (Kaguya) revealed a partial loss in the electron velocity distribution function due to the "gyro-loss effect", namely gyrating electrons being absorbed by the lunar surface. The Moon enters the Earth's magnetosphere for a few days around full moon, where plasma conditions are significantly different from those in the solar wind. When the magnetic field is locally parallel to the lunar surface, relatively high-energy electrons in the terrestrial plasma sheet with Larmor radii greater than SELENE's orbital height strike the lunar surface and are absorbed before they can be detected. This phenomenon can be observed as an empty region in the electron distribution function, which is initially isotropic in the plasma sheet, resulting in a non-gyrotropic distribution. We observed the expected characteristic electron distributions, as well as an empty region that was consistent with the presence of a relatively strong electric field (∼10 mV/m) around the Moon when it is in the plasma sheet.

Original languageEnglish
Article numberL19202
JournalGeophysical Research Letters
Issue number19
Publication statusPublished - Oct 1 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


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