Solar eclipse stamp changes from eclipsed sun to full moon

To commemorate the total solar eclipse over the US in August, the U.S. Postal Service is releasing a landmark stamp that does something no other stamp can.

The Total Solar Eclipse Forever stamp, which will be issued June 20, changes when you touch it from an image of the eclipsed sun to one of the full moon.

On August 21, the moon will slip between the sun and Earth, casting a shadow that will create the first

over the U.S. in 38 years.

In a swath of the country from South Carolina to Oregon, darkness will reign in the middle of the day for a full two minutes and 40 seconds, beginning at 1:25 p.m. in the Eastern time zone.

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

Thermochromic ink makes the stamp work. Using the heat of your finger, the 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 this 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 back of the stamp will have a map of the eclipse path.

Read more here. 

Cox Media Group