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Earth-orbiting spacecraft that allows celestial objects and radiation to be studied from above the atmosphere. Astronomy from Earth's surface is limited to observation in those parts of the electromagnetic spectrum (see electromagnetic radiation) that are not absorbed by the atmosphere. Those parts include visible light and some infrared radiation and radio waves. The ability to place instruments in space opens all regions of the spectrum to observation. Even when operating in those wavelengths that penetrate to Earth's surface, an observatory in space avoids the problems of seeing caused by atmospheric turbulence and airglow.