The heat of your finger will change the picture on these stamps commemorating the coming eclipse.
USPSNot everyone will get to see the August 21 total solar eclipse, which will be visible in portions of only 14 US states. But everyone can make their own eclipse with new heat-sensitive postage stamps coming June 20 from the United States Postal Service.
The stamp uses two photos, both taken by Arizona astrophysicist Fred Espenak, who's also known as Mr. Eclipse. The first photo shows a total solar eclipse seen from Jalu, Libya, in 2006. By applying body heat from your thumb or fingers -- aka when you touch the stamp -- and gently rubbing, a full-moon photo is revealed. As the image cools, it reverts back to the eclipse photo.
The neat trick utilizes the first US stamp application of thermochromic ink. The stamp is being issued as a Forever stamp, meaning it's always equal in value to the current first-class mail 1-ounce price.
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