Don’t forget Pluto
By the time the “Views of our Planets” stamp collection was released, Pluto had already been chopped off the list of solar system planets. But that didn’t imply that the dwarf planet wasn’t deserving of its own stamp.
Shortly after NASA’s New Horizons mission zipped past Pluto and its moons in 2015, USPS issued a special set of stamps for the dwarf planet. In 1991, USPS had issued a “Pluto: Not Yet Explored” stamp as a rallying cry to send a spacecraft to explore the object. At that time, Pluto was still considered a planet but it hadn’t yet been visited by a spacecraft. When the 2016 stamp was issued, Pluto had been explored by a spacecraft, but was no longer considered a planet.
