制约类地行星大气层和水体发育的主要因素  

THE MAIN ELEMENTS OF CONSTRAINT ON THE ATMOSPHERE AND HYDROSPHERE ORIGIN AND EVOLUTION OF THE TERRESTRIAL PLANETS

作　　者：欧阳自远[1] 邹永廖[2] 李春来[2] 刘建忠[2] 徐琳[1] 

机构地区：[1]中国科学院地球化学研究所,贵阳550002 [2]中国科学院国家天文台,北京100012

出　　处：《第四纪研究》2002年第6期558-567,共10页Quaternary Sciences

基　　金：中国科学院知识创新工程项目 (批准号 :KZCX2 - 115 );中国科学院高技术与发展局专项项目 (批准号 :KGCX2 - 4 0 6 )

摘　　要：根据行星探测的资料 ,综合分析了水星、金星、地球 (包括月球 )、火星的大气层和水体的发育特征 ,对比了金星、火星的大气层与水体同地球的差异。类地行星质量小、体积小、密度大、旋转慢、卫星少甚至没有、挥发性元素较类木行星少、距离太阳较近 ,早期残留的原始大气层已经被早期太阳在金牛变星阶段的强烈太阳风所驱赶 ,加上巨大而频繁的撞击作用 ,使原始大气层被驱赶殆尽。现在的大气层是次生的 ,是由行星内部的去气作用形成的。类地行星的大气层、水体的发育和表生作用的特征与行星的质量大小 (表征行星内部能量的大小和构造活动的强烈及持续时间 )及行星与太阳的距离等因素有关。在类地行星中 ,地球和金星质量最大 ,逃逸速度最大 ,可将更多的气体“束缚”在它们表面 ,因此它们的大气有着复杂的组成和较大的密度。火星质量较小 ,逃逸速度不到地球的一半 ,在漫长的演化历史中 ,大气逐渐逸散进入太空 ,大气密度变得很稀薄。水星质量更小 ,而且最靠近太阳 ,不仅太阳风的驱赶作用强烈 ,而且表面温度高 ,气体分子的热运动更加剧烈 ,加剧了大气的逸散 ,所以水星的大气层极为稀薄 ,并且主要为太阳风成分。月球质量最小 ,几乎没有大气层 ,更没有水体的发育。行星的热演化历史对大气层和水体发育具有重要的制?In this paper, the authors analyze the original and evolutional characteristics of the atmosphere and hydrosphere of the Mercury, Venus, Earth (including the Moon), Mars, discuss the differences of the atmosphere and hydrosphere among the Venus, Mars and the Earth. Compared with the outer planets of the solar system, the terrestrial planets have small mass and volume, high density, slow rotation, less or no satellite, low volatile element abundances,near the Sun, lost all of their original atmosphere driven by the strong solar wind during Taurus Period,combined with the frequent and heavy impacts, the present atmosphere is secondary and come from the leaving of gases in interiors. The formation and evolution of the atmosphere and hydrosphere of the terrestrial planets were controlled by their mass (representing their energy as well as the duration and intensity of tectonic activities), the distance from the sun, and other elements. Generally, among the terrestrial planets the Earth and Venus characterized by the haviest mass, highest escape velocity, tied up much more gases which are more complicated in components and higher in density. The Mars with light mass and a velocity of no more than the half of the Earth′s, the gases on its surface gradually escaped into the deep space and the atmosphere became rare. The Mercury is the lightest planet in the terrestrial planets and nearest to the sun on which not only the solar wind but also thermal motions of molecules of gases (high temperature) is strong, and the gases easily escape into the space leaving rather rare atmosphere and have the solar wind properties. The Moon has the minimum mass with almost no atmosphere and hydrosphere. Overall, the thermal history of planets,the distance from the sun and their mass puts important effects on their atmosphere and hydrosphere formation and evolution.

关 键 词：类地行星 大气星 水体 制约因素 行星质量 热演化程度 

分 类 号：P185[天文地球—天文学]