Joe Alterio has designed 3 posters for the Institute of Physics which change their appearance in the presence/absence of light or heat. They will be put up in schools around the UK in efforts to rekindle children’s fascination with science. Of the three posters, one reacts to heat and the other two to the light. There’s a mention of them being made for sale to the public and I’m sure there’s enough demand, personally I’d love one of the Earth/Moon ones.

You can read the full article and see the posters on Joe’s website here: http://joealterio.com/2010/07/get-physical/

This is the Earth/Moon one. The top half is visible when the lights are on, the other half when they’re off.