Nature and variability of Mercury's sodium atmosphere
Nature and variability of Mercury's sodium atmosphere
复制标题
水星钠大气的性质和变化
作者：
W. Smyth
我们对水星的认识几乎完全来自对水手10号宇宙飞船三次飞掠水星（1974年3月29日、1974年9月21日和1975年3月16日）期间获得的有限数据的分析。地面观测在水星上惊人地发现了钠的大气层，这不仅重新点燃了人们对这颗行星的兴趣，而且通过持续不断的地面观测，开辟了探索这颗行星、它的大气层以及它与太阳风的相互作用的一条充满希望的新途径。在这里，我研究了钠大气的特殊行为和可能的空间特征。由于钠原子承受的太阳辐射压力大且变化极大，而且表面可能存在非热源，所以钠大气的大小和形状会随着水星绕太阳的轨道位置而发生巨大变化，从而为远程研究提供了有价值的特征。
Our knowledge of Mercury has been derived almost exclusively from the analysis of a limited amount of data acquired by the Mariner 10 spacecraft during its three flybys of the planet (29 March 1974, 21 September 1974 and 16 March 1975). The surprising discovery of a sodium atmosphere on Mercury from ground-based observations1 has not only re-kindled interest in the planet but has also opened, through continuing ground-based observations2,3, a new and promising way to explore the planet, its atmosphere and its interactions with the solar wind. Here I examine the peculiar behaviour and likely spatial character of the sodium atmosphere. Because of the large and extremely variable solar radiation pressure experienced by sodium atoms and the suggested presence3 of a non-thermal surface source, the size and shape of the sodium atmosphere can vary tremendously with Mercury's orbital location about the Sun, thus providing valuable signatures for remote study.