IR Atmospheric Windows  The Universe sends us light at all
wavelengths of the electromagnetic spectrum. However, most of
this light does not reach us at ground level here on Earth. Why?
Because we have an atmosphere which blocks out many types of
radiation while letting other types through. Fortunately for
life on Earth, our atmosphere blocks out harmful, high energy
radiation like X-rays, gamma rays and most of the ultraviolet
rays. It also block out most infrared radiation, as well as very
low energy radio waves. On the other hand, our atmosphere lets
visible light, most radio waves, and small wavelength ranges of
infrared light through, allowing astronomers to view the
Universe at these wavelengths.  Most of the infrared light
coming to us from the Universe is absorbed by water vapor and
carbon dioxide in the Earth's atmosphere. Only in a few narrow
wavelength ranges, can infrared light make it through (at least
partially) to a ground based infrared telescope.  The Earth's
atmosphere causes another problem