“The earth’s atmosphere is an imperfect window on the universe. Electromagnetic waves in the optical part of the spectrum (that is waves longer than X rays and shorter than radio waves) penetrate to the surface of the earth only in a few narrow spectral bands The widest of the transmitted bands corresponds roughly to the colors of visible light waves in the flanking ultraviolet and infrared regions of the optical spectrum are almost totally absorbed by the atmosphere. In addition atmospheric turbulence blurs the images of celestial objects even when they are viewed through the most powerful ground-based telescopes in an article promoting the construction of the Hubble Space Telescope.”
