* Interstellar dust. Space is not completely empty. It contains a very thin gas of particles, called interstellar dust. These particles can scatter sunlight, which is what makes them visible in space pictures.
* Starlight. Stars are very bright objects, and their light can travel for long distances. Even when a star is very far away, its light can still be detected by a camera.
* Long exposure times. Space pictures are often taken with long exposure times. This means that the camera's shutter is left open for a long time, allowing more light to collect on the film or sensor. This can make stars appear brighter and more numerous in space pictures than they actually are.
The next time you see a space picture, take a close look at the stars. They are a reminder of the vastness of the universe and the incredible distances that light can travel.
