Leslie's cube
The upper pictures were taken with an infrared camera, the lower ones as a public black-and-white photo. The cube (Leslie cube) is completely at the same temperature (55 ÂșC). Surfaces painted black have a higher emissivity, i.e. they emit more thermal radiation and therefore appear warmer in an infrared camera. Shiny aluminum surfaces have poor emissivity, so they appear colder in a thermal camera. You can see the reflections of the hand on the aluminum surfaces.
© Pieter Kuiper