When mountaineers climb Mount Everest, they routinely carry oxygen cylinders, devices that allow them to breathe freely at high altitudes. This is necessary because the closer you get to the edge of Earth’s atmosphere, the less oxygen there is available compared with the plentiful amounts found at sea level.
This is just one example of how variable Earth’s atmosphere is and showcases the elemental makeup of its layers, from the troposphere, near sea level, to the exosphere, in its outermost regions. Where each layer ends and begins is defined by four key traits, according to the National Weather Service (opens in new tab): temperature change, chemical composition, density and the movement of the gases within it.
So, with this in mind, where does Earth’s atmosphere actually end? And where does space begin?
