Pluto

]] Pluto was formerly considered the farthest planet from the Sun, and the smallest]], from 1930 until its reclassification in 2005 by astronomers as a dwarf planet. In 2008, following a conference and debate by the International Astronomical Unbion, which failed to establish consensus for the definition of a planet, a press release announced a new term, plutoid, defined as objects that orbit the sun at a semi-major axis greater than Neptune's and sufficient mass to be nearly spherical. While IAU's Committee on Small Bodies Nomenclature announced and adopted it (as did the executive committee), another IAU group, for Planetary System Nomenclature, rejected it. The term's adoption by astronomers has varied since then.

In 2015, the spacecraft New Horizons flew by Pluto, delivering new data and observations about its measurements and moons. The former planet was not, despite popular jokes, named after Mickey Mouse's dog, but after the Greek god of the Underworld.

In most older Muppet/Sesame Street books, Pluto is still present as a planet. In 1987's A Visit to the Sesame Street Museum, Ernie glances at Pluto in a solar system display.

Also in 1987, in Gonzo and the Great Race, Baby Gonzo races Skeeter across the globe and into space, with Pluto as the final destination. Skeeter seemingly retained her interest in the planets, since in The Trouble with Twins (1993), she decides to create a citrus solar system for her science project, selecting a lemon as Pluto.