When the sky goes dark on August 21, much of the continental United States will pause to celebrate. And with good reason: The total solar eclipse that will cross from coast to coast will be the first of its kind to touch U.S. soil in nearly a century. And what better way to celebrate than by bringing the eclipse into your own home?
The United States Postal Service just issued a new Forever stamp that lets you look at the eclipse without worrying about your eyesight. The stamp features an eclipse, but by placing a finger on top of the image, the heat of your body reveals a picture of our glorious moon taken by NASA astrophysicist Fred Espenak. This stamp incorporates technology that’s never been used before with these tiny works of art: thermochromic ink that responds to the body's heat.
You might recognize thermochromic ink from other everyday objects. One early application was mood rings. First introduced in the 1970s, they used liquid crystals that responded to body heat to reveal supposed truths about your inner state—with a side effect of looking pretty groovy. As Nathan Chandler notes for How Stuff Works, thermochromic dye inks also give cans of beer their catchy color shifts. However, the ink is so sensitive to UV light that the USPS will sell special envelopes for those who want to protect the stamp.
Though the stamp is the first to duplicate an eclipse effect, it’s certainly not the first stamp to show one. Espenak would know: He collects solar eclipse stamps from all over the world. In a press release, he says that he’s excited about spreading the news about the United States’ great eclipse far and wide.
With only two months to go until the eclipse, anticipation is rising. As CBS News reports, places like Makanda, Illinois, which is directly in the eclipse’s path, are preparing for an onslaught of eclipse-seeking tourists eager to spend the moments of transit in the event’s most complete shadow. And as Samantha Mathewson writes for Space.com, national parks like Grand Teton National Park and Fort Laramie National Historic Site are not just prepping for more visitors, but planning special events to help them make the most of their trip.
The eclipse won’t look the same all over the United States, but the color-shifting stamp will—and it will look even better next to a postmark from the site of your own eclipse-chasing adventure.