From usps.com - see
http://about.usps.com/news/national-releases/2017/pr17_020.htm ;
"The Postal Service will soon release a first-of-its-kind stamp that changes
when you touch it. The Total Eclipse of the Sun Forever stamp, which
commemorates the August 21 eclipse, transforms into an image of the Moon from
the heat of a finger.
"The Total Eclipse of the Sun Forever stamps may be pre-ordered at
usps.com/shop in early June for delivery following the June 20 nationwide
issuance.”
Alex