From our perspective on Earth, space seems like a vastly unlimited horizon that stretches from one to the other end of the universe. We don’t know if there are even any bounds or limits that holds the universe or if the universe itself holds everything else in it. In that case, where is the edge of space?
In this paper I revisit proposed definitions of the boundary between the Earth’s atmosphere and outer space, considering orbital and suborbital trajectories used by space vehicles. In particular, I investigate the inner edge of outer space from historical, physical and technological viewpoints and propose 80 kilometers as a more appropriate boundary than the currently popular 100 km Von Kármán line.
(Video credit: Sixty Symbols)