Get yourself a pen pal because you're going to want to snatch up these collectible stamps from the US Postal Service. The USPS is releasing a commemorative stamp that changes into the upcoming solar eclipse on Aug. 21 simply by pressing your finger on it.
The stamp, which will be released on June 20, uses thermochromic ink to change the image of the solar eclipse into the moon. Both the photo of the moon and the solar eclipse was taken by astrophysicist Fred Espenak, from a previous solar eclipse seen on March 29, 2006 from Jalu, Libya.
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If you want to save the stamp as part of a collection, the USPS will also sell a special envelope to hold it. Using the stamps for normal mail? You don't need the envelope, but you should keep the stamp out of direct sunlight, advises the USPS.