<P> In 1976, eight equatorial states (Ecuador, Colombia, Brazil, Congo, Zaire, Uganda, Kenya, and Indonesia) met in Bogotá, Colombia . With their "Declaration of the First Meeting of Equatorial Countries", or "the Bogotá Declaration", they claimed control of the segment of the geosynchronous orbital path corresponding to each country . These claims are not internationally accepted . </P> <P> A spacecraft enters orbit when its centripetal acceleration due to gravity is less than or equal to the centrifugal acceleration due to the horizontal component of its velocity . For a low Earth orbit, this velocity is about 7,800 m / s (28,100 km / h; 17,400 mph); by contrast, the fastest manned airplane speed ever achieved (excluding speeds achieved by deorbiting spacecraft) was 2,200 m / s (7,900 km / h; 4,900 mph) in 1967 by the North American X-15 . </P> <P> To achieve an orbit, a spacecraft must travel faster than a sub-orbital spaceflight . The energy required to reach Earth orbital velocity at an altitude of 600 km (370 mi) is about 36 MJ / kg, which is six times the energy needed merely to climb to the corresponding altitude . Spacecraft with a perigee below about 2,000 km (1,200 mi) are subject to drag from the Earth's atmosphere, which decreases the orbital altitude . The rate of orbital decay depends on the satellite's cross-sectional area and mass, as well as variations in the air density of the upper atmosphere . Below about 300 km (190 mi), decay becomes more rapid with lifetimes measured in days . Once a satellite descends to 180 km (110 mi), it has only hours before it vaporizes in the atmosphere . The escape velocity required to pull free of Earth's gravitational field altogether and move into interplanetary space is about 11,200 m / s (40,300 km / h; 25,100 mph). </P> <P> 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 . </P>

Where is most of the space found in an atom