At a public ceremony in Laramie on June 20, the United States Postal Service unveiled the “Total Eclipse of the Sun” Forever stamp. The ceremony was be the national debut of this stamp that transforms using the heat of a finger.

By touching the stamp image of the eclipse, an underlying image of the Moon is revealed. Once the stamp cools, the image reverts back to the eclipse.  The stamp is now sold at post offices nationwide.

In the first U.S. stamp application of thermochromic ink, the Total Solar Eclipse stamps will reveal a second image. Using the body heat of your thumb or fingers and rubbing the eclipse image will reveal an underlying image of the Moon. The image reverts back to the eclipse once it cools.

Thermochromic inks are vulnerable to UV light and should be kept out of direct sunlight as much as possible to preserve this special effect. Art director Antonio Alcalá of Alexandria, VA, designed the stamp.

The stamp debut event followed the University of Wyoming Art Museum’s annual summer solstice celebration.

At exactly noon, the sun shone through a solar tube in the ceiling of the Rotunda Gallery and illuminated a silver dollar that is set into the center of the gallery’s floor.

In attendance at the event were a NASA astrophysicist, a University of Wyoming Department of Physics and Astronomy professor, Fred Espenak, the photographer of the stamp image and Eclipse expert and several USPS executives.

A total eclipse of the sun will occur on Aug. 21. The solar eclipse happens as the moon completely blocks the visible solar disk from view, casting a shadow on Earth.

Tens of millions of people in the United States hope to view this rare event, which has not been seen on the U.S. mainland since 1979. The eclipse will travel a narrow path across the entire country for the first time since 1918.

The 70-mile-wide shadow path of the eclipse, known as the “path of totality,” will traverse the country diagonally, appearing first in Oregon (mid-morning local time) and exiting some 2,500 miles east and 90 minutes later off the coast of South Carolina (mid-afternoon local time) passing through portions of 14 states.

The Total Eclipse of the Sun stamp image is from a photograph taken by retired NASA astrophysicist Fred Espenak of Portal, Ariz., who is considered by many to be the world’s leading authority on total solar eclipses with 27 under his belt.  The photograph shows a total solar eclipse seen from Jalu, Libya, on March 29, 2006.

“I’m honored to have my images on this unique stamp,” said Espenak, who began collecting eclipse stamps after witnessing his first as a teenager. “A total eclipse of the sun is simply the most beautiful, stunning and awe-inspiring astronomical event you can see with the naked eye.”

The pane of 16 Forever stamps are available at Post Office facilities nationwide on June 20 and may also be ordered online for home delivery.