Landsat satellites carry sensors that record “light,” or portions of the electromagnetic spectrum, as it reflects off the Earth.
|electromagnetic spectrum |
The entire range of electromagnetic radiation. At one end of the spectrum are gamma rays, which have the shortest wavelengths and high frequencies. At the other end are radio waves, which have the longest wavelengths and low frequencies. Visible light is near the center of the spectrum.
The family of electromagnetic waves. The electromagnetic spectrum, starting from the waves with the longest wavelengths (and least energy), consists of radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma radiation. Members of the family differ from one another only in their wavelength, or frequency. For example, the wavelength of blue light is roughly half that of red light, but the waves corresponding to the two colors are otherwise identical.