At sea level, air pressure is about 14.7 pounds per square inch (1 kilogram per square centimeter), and the atmosphere is relatively dense. The layers are separated based on temperature according to the National Institute of Water and Atmospheric Research (opens in new tab) (NIWA).The atmosphere thins out in each higher layer until the gases dissipate in space. (Image credit: Future) (opens in new tab) The five main layers of the Earths atmosphere. Since 99.99997 percent of Earth's atmosphere is located below this point, it's considered a reasonable height to draw the boundary between Earth and space.

Though not everyone agrees where space actually begins, most scientists agree that the Kármán line, situated 62 miles (100 km) above sea level, marks the transition point between Earth and space.

According to education site Vision Learning (opens in new tab) Earth's atmosphere is composed of approximately 78 percent nitrogen, 21 percent oxygen, 0.93 percent Argon, 0.04 percent carbon dioxide as well as trace amounts of neon, helium, methane, krypton, ozone and hydrogen, as well as water vapor.īut just how high does Earth's atmosphere extend? Well that depends on who you ask! According to NASA (opens in new tab) the upper layer of Earth's atmosphere - the exosphere - extends up to 6,200 miles (10,000 km), above which the atmosphere and space blend. Though oxygen is crucial for life on Earth, it is not the primary component of our atmosphere.

Outside of Space by Timothy Burns