LARAMIE, Wyo. (AP) — The U.S. Postal Service has officially unveiled a first-of-its kind stamp that transforms with the touch of a finger and is dedicated to this summer's total solar eclipse.

The 49 cent stamp uses temperature-sensitive ink. When a person touches it, the body heat transforms the image of the blacked-out sun into the moon. Once the figure is removed, the eclipse reappears.

In addition, on the back of the sheet of stamps is a map of the eclipse's diagonal path across the U.S. on Aug. 21, when the moon comes between the sun and Earth.

It will be the first total solar eclipse visible in the contiguous United States since 1979 and the first one coast to coast since 1918.

Tuesday's ceremony was timed with the first day of summer.