Structure of the ionized lunar sodium and potassium exosphere: Dawn-dusk asymmetry

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

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


We present latitude and longitude distributions of Na+ and K+ fluxes from the Moon derived from Kaguya low-energy ion data. Although the latitude distribution agrees with previous ground-based telescope observations, dawn-dusk asymmetry has been determined in the longitude distribution. Our model of the lunar surface abundance and yield of Na and K demonstrates that the abundance decreases to approximately 50% at dusk compared with that at dawn due to the emission of the exospheric particles assuming the ion fluxes observed by Kaguya are proportional to the yield. It is also implied that the surface abundance of Na and K need to be supplied during the night to explain the observed lunar exosphere with dawn-dusk asymmetry. We argue that the interplanetary dust as well as grain diffusion and migration/recycling of the exospheric particles may be major suppliers. Key Points Kaguya data present structure of the ionized lunar alkali exospheres We found dawn-dusk asymmetry in the longitude distribution Our model shows that the surface abundance decreases to 50%

Original languageEnglish
Pages (from-to)798-809
Number of pages12
JournalJournal of Geophysical Research: Planets
Issue number4
Publication statusPublished - Apr 2014

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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