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EM Spectrum: Near IR

Near Infrared and the Electromagnetic Spectrum

Wavelength bands within the visible spectrum are defined by color. The range of wavelengths that span the infrared spectrum is roughly 40 times greater than that of the visible spectrum. Because the infrared region is so large, there is quite a bit of confusion when one uses the term "infrared". Technologies and activities presented in Measuring Vegetation Health deal with the near infrared, which is quite close to the red visible spectrum and quite far from the thermal infrared wavelengths, which is commonly referred to as "heat."

Although our bodies do emit IR, the wavelengths are in the far or thermal IR region. The IR detected with digital cameras and light emitting diodes (LEDs) in TV remote controls is in the near IR region, which is generated from very hot light sources. All objects emit light, but cooler objects emit light of longer wavelengths. Hotter bodies emit light of shorter wavelengths. For example, blue stars are hotter than red stars (blue is a shorter wavelength than red).

Remember, near infrared is not heat.