New Eclipse Stamp Reveals Hidden Moon Image When Rubbed

The new Total Eclipse of the Sun stamp contains a hidden image of the full moon only revealed when you rub it with your finger. During a total solar eclipse, the moon comes directly between the Earth and sun and blocks it from view. The black disk is the silhouetted moon. Credit: USPS

Guess who’s got eclipse fever? On June 20, the U.S. Postal Service will release a special stamp to commemorate the August 21 total eclipse of the sun. No ordinary stamp, it’s the first to contain a special thermochromic ink that changes when you touch it. The blackened sun, ringed by the solar corona, transforms into an image of the full moon from the heat of a finger.

Tens of millions of people in the United States including yours truly hope to view this rare event, the first total solar eclipse to cross the mainland U.S. since 1979. It’s also the first to cross the entire country from the Pacific to Atlantic coasts since 1918. The path will run west to east from Oregon to South Carolina and will include portions of 14 states.

The back of the stamp pane provides a map of the August 21 eclipse path and times it may appear in some locations. Click here to view and download detailed maps showing where the eclipse is visible. Credit: USPS

The stamp will be unveiled on June 20 (the date of the summer solstice) at 1:30 p.m. at the Art Museum of the University of Wyoming (UW) in Laramie.  Visitors are encouraged to arrive at 11:30 a.m. to witness a unique solar alignment that happens at noon every summer solstice in the UW Art Museum’s Rotunda Gallery, where a single beam of sunlight shines on a silver dollar embedded in the floor.

The stamp image is a photograph taken by astrophysicist Fred Espenak, better known as Mr. Eclipse, of Portal, AZ, that shows a total solar eclipse seen from Jalu, Libya, on March 29, 2006. Espenak is both an astrophotographer and creator of the global maps showing eclipse paths that are often featured in this blog.

This is the original image used to create the stamp. It’s composite image from 22 separate exposures. Espenak used a Nikon D200 and Vixen 90mm f/9 Fluorite Refractor (exposures 1 to 1/1000 second) and a narrow radial filter. Credit and copyright: Fred Espenak

One of my earliest hobbies was stamp collecting, and although I don’t collect anymore, this stamp has me psyched. It uses the body heat of your thumb or fingers to reveal a second image. Rubbing the eclipse image will reveal an underlying image of the Moon, also snapped by Espenak, which reverts back to the eclipse once it cools.

Because thermochromic inks are vulnerable to UV light, the post office recommends they be kept out of direct sunlight as much as possible to preserve the special effect. To help ensure longevity, the Postal Service will be offering a special envelope to hold and protect the stamp pane for a nominal fee. The Total Eclipse of the Sun stamp will be another in the series of Forever stamps, which are always  equal in value to the current First-Class Mail 1-ounce price.