The redshift mirror was a project built during the Dot Astronomy conference to try and visualise the resdhift or blueshift as objects in the universe move away or towards us
It uses a Kinect camera to monitor a scene and estimates the velocity of objects in the scene either towards or away from the camera by diffing frames. Objects moving towards the camera are given a red color which is more intense the faster they are moving towards the camera and objects moving away are given a blue color. Stationary objects are invisible.
The most interesting interactions came from watching people turn. One side was redshifed the other blue, this is how we measure the rotation speeds of galaxies and the mirror became a illustrative example of this