US Postal Service issues lunar eclipse stamp that changes when you touch it

The US Postal Service will soon release a first-of-its-kind stamp that changes when you touch it.The Total Solar Eclipse stamp will show an eclipse that transforms into an image of the moon from the heat of a finger. The stamp uses thermochromic ink to make the transformation possible.The stamp will be issued in June to commemorate the eclipse that will occur in the United States on 21 August. It will be the first eclipse seen on the U.S. mainland since 1979.