外太空指的是地球稠密大气层之外的空间区域,并没有明确的界线分野。一般定义为大约距离地球表面1000千米之外的空间。 人类对外太空的好奇和探索从未停止过，中国“神五”、“神六”的成功发射标志着中国对外太空的探索步入了世界的先进行列。 Outer space Layers of Atmosphere - not to scale (NOAA) Outer space , sometimes simply called space , refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies . Outer space is used to distinguish it from airspace (and terrestrial locations). Contrary to popular understanding, outer space is not actually empty (i.e. a perfect vacuum ) but contains a low density of particles, predominantly hydrogen plasma , as well as electromagnetic radiation , dark matter and dark energy . Contents 1 Earth's boundary 2 Solar System 3 The "Vacuum of Space" 4 Satellites 5 Milestones on the way to space 6 Regions of outer space 7 Space does not equal orbit 8 See also 9 References 10 External links Earth's boundary There is no clear boundary between...