Leslie cube

Leslie's cube is a device used in the measurement or demonstration of the variations in thermal radiation emitted from different surfaces at the same temperature.

The mirror-like, polished face of the aluminum cube emits thermal radiation weakly, as indicated by the blue color.

The reflection of the experimenter's hand is green, which corresponds to a high emissivity surface near body temperature (37 °C).

A modern version of Leslie's Cube is part of the structure of a small earth-orbiting satellite known as FUNcube-1 and registered as a Dutch spacecraft.

Launched in November 2013, it demonstrates the absorption and emission of solar radiation in space as the satellite orbits in full sunlight, eclipse and rotates around its three axes.

A Leslie cube (left) and a thermal detector (right)
The upper photographs of Leslie's cube (in color) are taken using an infrared camera; the black and white photographs underneath are taken with an ordinary camera. The face of the cube that has been painted black emits thermal radiation strongly. The polished face of the aluminum cube emits much more weakly, and the reflected image of the warm hand is clear.
FUNcube-1 in the cleanroom before launch
Draper's 1861 description of the Leslie cube