Performing astronomy from the Earth's surface is limited by the filtering and distortion of electromagnetic radiation due to the atmosphere. This makes it desirable to place astrononomic observation devices into space.

The most famous example of such a device is arguably the Hubble Space Telescope (HST), which allows observations within the visible and adjacent spectral ranges with previously unavailable sharpness. As it is orbiting Earth outside the atmosphere it is neither subject to distortion due to thermal turbulences of the air nor to light pollution from artificial light sources on the Earth. (Remarkably, the HST's brilliance now has a rival in the terrestrial Very Large Telescope which can counter turbulences with the help of its novel adaptive optics.)

But space-based astronomy is even more important for frequency ranges which are outside of the optic window and the radio window, as the two only wavelength ranges of the electromagnetic spectrum are called, that are not severely attenuated by the atmosphere.

For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current important stand within astronomy only due to orbiting satellites with X-ray telescopes such as ROSAT.