Every satellite image you have seen, from weather maps to the photo of your street on a mapping app, was taken by a sensor hundreds of kilometres above Earth, moving at around 27,000 kilometres per hour, in conditions no ordinary camera could survive. Yet the basic idea is familiar: a sensor collects light reflected or emitted by the ground and turns it into an image. The differences lie in the orbit, the sensor, and the processing that turns raw data into a picture you can understand.

This guide explains those three pieces in plain language, without assuming any physics background.