Mendillo M, Baumgardner J
Center for Space Physics, Boston University, Massachusetts 02215, USA.
Nature. 1995 Oct 5;377(6548):404-6. doi: 10.1038/377404a0.
The properties of the Moon's rarefied atmosphere, which can be traced through observations of sodium and potassium, provide important insights into the formation and maintenance of atmospheres on other primitive Solar System bodies. The lunar atmosphere is believed to be composed of atoms from the surface rocks and soil, which might have been sputtered by micrometeorites, by ions in the solar wind, or by photons. It might also form by the evaporation of atoms from the hot, illuminated surface. Here we report the detection of sodium emission from the Moon's atmosphere during a total lunar eclipse (which occurs when the Moon is full). The sodium atmosphere is considerably more extended at full Moon than expected--it extends to at least nine lunar radii--and its brightness distribution is incompatible with sources involving either solar-wind or micrometeorite sputtering. This leaves photon sputtering or thermal desorption as the preferred explanations for the lunar atmosphere, and suggests that sunlight might also be responsible for the transient atmospheres of other primitive bodies (such as Mercury).
月球稀薄大气层的特性可通过对钠和钾的观测来追踪，这为了解其他原始太阳系天体大气层的形成和维持提供了重要见解。月球大气层被认为是由表面岩石和土壤中的原子组成的，这些原子可能是被微流星体、太阳风中的离子或光子溅射出来的。它也可能由受热、光照的表面原子蒸发形成。在此，我们报告了在月全食（满月时发生）期间检测到月球大气层中的钠发射。满月时钠大气层的范围比预期大得多——它至少延伸到九个月球半径——其亮度分布与涉及太阳风或微流星体溅射的来源不相符。这使得光子溅射或热解吸成为月球大气层的首选解释，并表明阳光可能也是其他原始天体（如水星）瞬态大气层的成因。
