A camera on a roof, facing north, shutter held open. The sky turns once a day around the pole, so every star draws an arc, and every arc sweeps the same angle. Only Polaris, a hair from the pole, stays nearly a point.
press and hold anywhere (or hold space) to open the shutter · release to close it · 1 2 3 change the sky · n for a new plate
shutter closed · nothing on the plate yet