Satellites have superpowers — they can survive in a vacuum, feed on sunlight, tirelessly observe the most remote corners of the Earth, and speed through space at over 17,000 miles per hour.

They can also see the unseeable.

Although many of the pictures from space you commonly see — Google Maps’ satellite view, NASA’s Blue Marble, or snapshots from the International Space Station — are ‘true color’ (taken using visible light), most Earth observation satellites also collect data with light invisible to humans — most commonly near infrared. Among other things, this type of light makes it easy to tell the difference between water and land (important for mapping), and can give a clear view of the Earth’s surface through smoke and haze that might otherwise block a satellite’s view.

Near-infrared light is just outside the range of human vision. It’s only a tiny bit redder (longer wavelength) than a red LED. This redder-than-red light behaves mostly like the light that makes up the colors of the visible spectrum. Near-infrared light travels through the air like normal light, and is usually observed after it’s been reflected off a surface. Other colors of infrared light—long-wavelength thermal infrared, for example—are less like visible light. In some ways, they’re downright weird—midwave infrared is blocked by water vapor, and brightness in thermal infrared is proportional to the temperature of a surface.