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Postal News: Eclipse of sun to be commemorated on a stamp in thermochromic ink
May 3, 2017

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The United State Postal Service will release a first-of-its-kind stamp that changes when you touch it.

The Total Solar Eclipse Forever stamp, which commemorates the Aug. 21 eclipse, transforms into an image of the moon from the heat of a finger.

Tens of millions of people in the United States hope to view the 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 path will run west to east from Oregon to South Carolina and will include portions of 14 states.

The first-day-of-issue ceremony will take place on June 20 at the Art Museum of the University of Wyoming in Laramie, Wyoming. The university will be celebrating the summer solstice.

The back of the stamp pane provides a map of the Aug. 21 eclipse path and times it may appear in some locations. Visit NASA at: www.nasa.gov/ to view detailed maps of the eclipse's path.

Thermochromic ink

The stamp image is a photograph taken by astrophysicist Fred "Mr. Eclipse" Espenak, of Portal, Arizona, that shows a total solar eclipse seen from Jalu, Libya, on March 29, 2006.

In the first U.S. stamp application of thermochromic ink, the 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, which Espenak also took. 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 the special effect. To help ensure longevity, the USPS will offer a special envelope to hold and protect the stamp pane for a nominal fee.

A total eclipse of the sun occurs when the moon completely blocks the visible solar disk from view, casting a shadow on Earth. The 70-mile-wide shadow path of the eclipse, known as the "path of totality," will traverse the country diagonally, appearing first in Oregon and exiting some 2,500 miles east and 90 minutes later off the coast of South Carolina.

A total solar eclipse provides us with the only chance to see the sun's corona - its extended outer atmosphere - without specialized instruments. During the total phase of an eclipse the corona appears as a gossamer white halo around the black disk of the Moon, resembling the petals of a flower reaching out into space.

Art director Antonio Alcala, of Alexandria, Virginia, designed the stamp. It is being issued as a Forever stamp, which is always equal in value to the current First-Class Mail 1-ounce price.

Phil Wiebold is a spokesman for U.S. Postal Service.

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