Colour-changing stamp to mark rare solar eclipse event in US

The US postal agency is issuing a first-of-its-kind postage stamp that morphs when touched - changing from the image of a total solar eclipse to that of the Moon.
On August 21 this year, US will witness a rare celestial event. For the first time in 38 years, the Moon will completely block the solar disk for a few minutes, creating a total eclipse of the Sun.
To mark the historic event, the US Postal Service is issuing the inspired postage stamp.
Conceived by graphic designer Antonio Alcala, the stamp features two layers of photographs.
The first image depicts a picture of a total eclipse observed in Libya in 2006.

When the warmth of your finger touches the black dot, an image of a full moon emerges.

The commemorative stamp uses special temperature- sensitive inks, 'The Quartz' reported.
On the back of the sheet of stamps, a map of the eclipse's shadow path, which will traverse 14 states as it moves east, from Oregon to South Carolina.
The Total Solar Eclipse stamps go on sale on June 20.