A range of wavelengths to which the Earth’s atmosphere is relatively transparent, so that astronomical observations can be made from the ground. The major windows are in the visible, infrared, and radio parts of the spectrum. The visible window extends from about 0.3 to 0.9 μ‎m. There are infrared windows at several wavelengths between about 1.25 and 30 μ‎m, and beyond 300 μ‎m. The radio window extends from about 1 cm to 30 m.