MARK GARLICK / SCIENCE PHOTO LIBRARY MARK GARLICK / SCIENCE PHOTO LIBRARY
Schematic illustration showing the relative height of space compared to the overall size of the Earth. Space does not have a definitive, hard boundary. The atmosphere gradually thins until at a somewhat arbitrary point called the Karman line, space is considered to begin. This is at a height of just 100 km, indicated here by the blue line. The outer shell, marked by the red line, corresponds to an altitude of 400 km - roughly that of the International Space Station (ISS). Seen relative to the Earth's landmasses (here showing North America), one can see just has tiny these heights are in the overall scheme.
Model release not required. Property release not required.