Pluto's demotion

A composite image of all the planets in our solar system except Pluto. From the top is Mercury (taken by the Mariner 10 spacecraft); Venus (taken by the Pioneer Venus Orbiter); a full disk of the Earth (taken by the Apollo 17 astronauts); the Moon and then Mars (captured from ground-based telescopes); and Jupiter, Saturn, Uranus and Neptune (as seen by the Voyager spacecraft).
Photo illustration courtesy of NASA
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