No Longer "Not Yet Explored"

Issued in 1991 by the United States Postal Service, the 29-cent Pluto commemorative stamp bore the words "Not Yet Explored." The July 14, 2015 flyby of Pluto by the New Horizons spacecraft definitively put to rest the implicit challenge expressed on the stamp. The stamp design at the bottom was proposed several years ago via petition to the US Citizens’ Stamp Advisory Committee of the USPS in anticipation of a successful mission.