Remote sensing is the sensing of different wavelengths of the Electro Magnetic Spectrum. A rainbow is a very good example of the Spectrum. It shows all possible colors or wavelengths of light. There are more "colors" than just what our eyes can see. There are wavelengths beyond both red and violet that are invisible to us.

There are about 2,800 man-made satellites orbiting earth as of the year 2000. The way that satellites "see" things is by reading wavelengths of light. Satellites that only sense one wavelength at a time are called single-spectra, satellites that sense a few at a time are called multi-spectra, and there are currently two satellites that sense thousands of wavelengths at a time. These are called hyper-spectra. One of the two hyper-spectra satellites is operated by the students at UNH.
(See UNH Satellite Projects) downloads: 3-d Satellite Animation
Animation Player.zip