Vineyards, large farms, and NASA all use near-infrared photography for assessing plant health, usually by mounting expensive sensors on airplanes and satellites.
Cooler objects glow faintly at longer wavelengths of light, while hotter objects glow more brightly at shorter wavelengths. Our Sun’s temperature is a blistering 5,778 K (9,940° F), which is so hot that it glows brightest at visible wavelengths of light (around 0.4 – 0.7 microns). People, who are much cooler (310 K, 98° F), actually glow as well, but in infrared light with a wavelength of around 10 microns. A micron is a millionth of a meter.