Figure 3.The electromagnetic spectrum marked by principle wavebands. Photosynthesis is driven by energy in the so-called “visible” light bands that appear to us as mixtures of red, green, blue. Light in the visible region has nanometer-scale wavelengths (1 billionth or 10-9 meters). Low-energy wave bands above ~740 nm (infrared, radar, microwave) are not used in photosynthesis but can be exploited in remote sensing applications. Note: the label “shortwave” at the ~100 meter band refers to the upper limit of the medium frequency first used for radio communication, not wavelength compared with that of visible light.