A special commemorative stamp issued by the U.S. Postal Service [USPS] in honor of the Aug. 21, 2017 eclipse won’t actually eclipse the main event – but it’s still pretty cool.

The ‘first-of-its-kind’ Forever stamp shows an image of the solar eclipse that transforms to the full moon when exposed to heat, as from the touch of a finger, an effect achieved through the use of thermochromatic ink, according to a USPS press release.

A map of the eclipse path with approximate times it will appear at certain points is printed on the back of the stamp pane.

Retired NASA astrophysicist Fred Espenak of Portal, Ariz., took the photograph the USPS used on the stamp. Espanek, who has seen 27 total solar eclipses, is widely considered the world’s leading authority on them.

The Postal Service has issued eclipse commemoratives in the past, and examples can be seen on the MrEclipse.com site.