Regions

Space is a partial vacuum: its different regions are defined by the various atmospheres and "winds" that dominate within them, and extend to the point at which those winds give way to those beyond. Geospace extends from Earth's atmosphere to the outer reaches of Earth's magnetic field, whereupon it gives way to the solar wind of interplanetary space. Interplanetary space extends to the heliopause, whereupon the solar wind gives way to the winds of the interstellar medium. Interstellar space then continues to the edges of the galaxy, where it fades into the intergalactic void. [edit]Geospace Aurora australis observed from the Space Shuttle Discovery, on STS-39, May 1991 (orbital altitude: 260 km) Geospace is the region of outer space near the Earth. Geospace includes the upper region of the atmosphere, as well as the magnetosphere.[68] The outer boundary of geospace is the magnetopause, which forms an interface between the planet's magnetosphere and the solar wind. The inner boundary is the ionosphere.[69] As the physical properties and behavior of near Earth space is affected by the behavior of the Sun and space weather, the field of geospace is interlinked with heliophysics; the study of the Sun and its impact on the Solar System planets.[70] The volume of geospace defined by the magnetopause is compacted in the direction o

the Sun by the pressure of the solar wind, giving it a typical subsolar distance of 10 Earth radii from the center of the planet. However, the tail can extend outward to more than 100–200 Earth radii.[71] The Van Allen radiation belt lies within the geospace. Geospace is populated by electrically charged particles at very low densities, the motions of which are controlled by the Earth's magnetic field. These plasmas form a medium from which storm-like disturbances powered by the solar wind can drive electrical currents into the Earth’s upper atmosphere. During geomagnetic storms two regions of geospace, the radiation belts and the ionosphere, can become strongly disturbed. These storms increase fluxes of energetic electrons that can permanently damage satellite electronics, disrupting telecommunications and GPS technologies, and can also be a hazard to astronauts, even in low Earth orbit. They also create aurorae seen near the magnetic poles.[72] Although it meets the definition of outer space, the atmospheric density within the first few hundred kilometers above the Karman line is still sufficient to produce significant drag on satellites.[65] This region contains material left over from previous manned and unmanned launches that are a potential hazard to spacecraft. Some of this debris re-enters Earth's atmosphere periodically.