To mark the historic total solar eclipse that will be visible Aug. 21 over a large portion of the continental U.S., the U.S. Postal Service will issue a first-of-its-kind stamp using thermochromic ink that changes when you touch it.

The Total Eclipse of the Sun forever stamp, designed by Antonio Alcalá of Alexandria, Va., transforms from a picture of the sun in eclipse into an image of the moon with the heat of a finger or thumb.

Read more: The sun will disappear for an hour and a half on Aug. 21
More: 10 best places to see this summer's total solar eclipse

Once it cools, it returns to a picture of the eclipse — with the moon appearing as a black disk obscuring the sun, whose wispy corona appears like ethereal white flower petals.

The stamp image is a photograph of a total solar eclipse seen from Jalu, Libya, in 2006. It was taken by astrophysicist Fred Espenak of Portal, Ariz.

The U.S. Postal Service says this is the first time it has used thermochromic ink on a stamp. The ink is sensitive to ultraviolet light, which means it should be stored away from direct sunlight. The Postal Service will sell a special envelope to safely store the stamps, which go on sale June 20 at a special event celebrating the summer solstice at the Art Museum of the University of Wyoming in Laramie.

The stamps may be preordered at starting in early June for delivery after June 20.

Contact Kristen Jordan Shamus: 313-222-5997 or