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New USPS Stamp Uses Thermochromic ‘Mood Ring’ Ink to Celebrate this Year’s Total Solar Eclipse

eclipse stamp
We haven’t been this excited about stamps since… ever.

The US Postal Service is letting us resurrect our inner 90s child in an adult way by releasing a limited-edition “mood ring” stamp in time for the total solar eclipse this August.

This will be the first USPS stamp that makes use of thermochromism… a fancy word for temperature-sensitive ink. This ink will create the mood ring illusion of a changing surface image, from darkened sun circle to a glowing moon.

Radical, man.

On the back of the sheet (released 0n the Summer Solstice, June 20th) the USPS included a map that tracks the total solar eclipse timeline. That way you can send to friends who live in the states that will get a front row seat to this outer-space marvel. (i.e. Oregon, Idaho, Wyoming, Nebraska, Missouri, Kentucky, Tennessee, and South Carolina.)

Science lesson: a total solar eclipse forms when a New Moon comes between the Sun and Earth, casting the darkest part of its shadow, the umbra, on Earth. The darkest part of the eclipse is almost as dark as night. Since there are five phases of this process, only few will see the event during its maximum eclipse. The result is a glowing ring (the diamond ring effect) where the sun’s edge beams from behind the moon.

Everyone with the USPS stamp, however, will see the maximum eclipse position in the initial image. To active the stamp special effects and change the image, just use the heat from your finger and press it over the stamp face. A sweet photo of the moon (taken by retired American astrophysicist Fred Espenak) will reveal itself.

The USPS is simultaneously tapping our adult social media tendencies by promoting the stamp via the hashtag #EclipseStamps. And so far it’s been a hit as people filter to Twitter to share their excitement. Some are even bummed there’s no pre-order option.

And since we can’t order in advance, we’ll be at the local post office, rocking light up sneakers and a Tamagotchi on our keychain, asking for the mood ring stamp…

It’s about time I wrote to grandma.