The delineation between Earth’s atmosphere and outer space is not a fixed boundary but rather a gradual transition. The concept often refers to the altitude at which atmospheric effects become negligible for certain practical purposes, such as aerodynamic flight. For instance, above a certain altitude, conventional aircraft cannot generate sufficient lift due to the air’s thinness.
Understanding this boundary is critical in aerospace engineering, space law, and meteorology. It informs the design of spacecraft and aircraft, the legal framework governing activities in space, and the study of atmospheric phenomena. Historically, defining this boundary has been essential for establishing national airspace sovereignty and regulating the use of space.
