Remote sensing is the science of obtaining and interpreting information from a distance, using sensors that are not in physical contact with the object being observed. Though you may not realize it, you are familiar with many examples. Biological evolution has exploited many natural phenomena and forms of energy to enable animals (including people) to sense their environment. Your eyes detect electromagnetic energy in the form of visible light. Your ears detect acoustic (sound) energy, while your nose contains sensitive chemical receptors that respond to minute amounts of airborne chemicals given off by the materials in our surroundings. Some research suggests that migrating birds can sense variations in Earth’s magnetic field, which helps explain their remarkable navigational ability.