12 Things Gen X Kids Were Taught In School That Have Since Been Disproven

One thing Gen X kids were taught in school that has since been disproven is that Pluto was a planet. The restructuring of the solar system came as a shock to many Gen X adults, who spent a lifetime holding onto the knowledge that the small, rocky planet was a planet, until they learned it wasn’t.

In 1930, astronomer Clyde Tombaugh discovered Pluto, which was considered to be the 9th planet in the solar system — until 2006, when the International Astronomical Union reclassified Pluto as a dwarf planet. According to the IAU, there are three basic factors that determine whether a celestial body is a planet: it has to orbit its host star, it has to be large enough to be mostly round, and it has to have “an important influence on the orbital stability of the other objects in its neighborhood.” Pluto meets the first two criteria, but not the third.

The 2006 IAU Resolution redefined our solar system as having eight planets. The resolution also defined a new class of objects, known as “dwarf planets,” which the planet-formerly-know-as-Pluto has been called from that point on. According to the IAU, a dwarf planet “is an object in orbit around the Sun that is large enough to pull itself into a nearly round shape but has not been able to clear its orbit of debris.”

The IAU recognized Pluto as “an important prototype of a new class of Trans-Neptunian Objects” known as plutoids, which helps astronomers classify different types of dwarf planets.

Gen X kids were between the ages of 25 and 41 when Pluto lost its status as a planet. This change meant that the Solar System maps Gen X kids used in classrooms officially became a thing of the past, much like Pluto the planet, itself.