To commemorate this summer’s total solar eclipse the U.S. Postal Service is releasing a new ‘Forever’ stamp that for the first time will feature thermochromic ink.
The Total Solar Eclipse Forever” stamp uses the heat of a person’s finger tips to change the stamp from an eclipsed Sun to an image of the moon.
Thermochromic inks are vulnerable to UV light and should be kept out of direct sunlight. The Postal Service is also offering for a nominal fee a special envelope to protect the stamps. The stamp photograph was taken by retired NASA Astrophysicist Fred Espenak, who has photographed many eclipses during his lifetime. The point of 'greatest eclipse' is in far Western Kentucky with a duration of totality lasting two minutes 41 seconds. The August 21st event is expected to draw around 50,000 people to Hopkinsville.
