So by looking at sunlight reflected from the Earth, scientists can see where pollutants are. But it's not quite that simple. Clouds absorb light, too. But TOMS solves the problem by looking at two different wavelengths of light. Wavelength is what gives light color.
Blue light has a shorter wavelength than red light.
TOMS sees light that has a very short wavelength, so short that we can't see it with our eyes. The wavelengths TOMS uses are both absorbed by clouds, but the aerosols only absorb the shorter wavelength. TOMS is one of several sensors that NASA has in space to keep an eye on Earth. The SeaWiFs satellite, designed to study Earth's oceans, has recorded many images of smoke.