Rub This Stamp with Your Finger & It Switches from an Image of an Eclipse to a Photograph of the Full Moon

Last month we featured a story with a wealth of information from Canon on how to photograph the once-in-a-life total eclipse of the sun that will be visible from coast to coast on August 21st.

To commemorate this rare event, which last occurred in 1918, the U.S Postal Service is issuing a forever stamp with two images by noted eclipse photographer Fred Espenak. What makes this stamp unusual is that it’s the first ever to overlay two images printed with “thermochromatic” ink: When you rub your finger over the black moon disk blocking the sun, the stamp transforms into an image of the full moon.

An astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, Espenak is also the webmaster of a personal site devoted to eclipse photography.

Eclipse expert Fred Espenak

Espenak has had a life-long passion for astrophotography and says he first became interested in eclipses after observing a total solar eclipse in 1970. Since then he’s made over 20 eclipse expeditions throughout the world. He’s lectured extensively on photographing the night skies and his images have been widely published online and in print.

You can see more from Espenak on his eclipse website, and be sure to look at our earlier story with everything you need to know about photographing the rare August 21 event

Via Sky & Telescope