Summary
Highlights
The video starts by highlighting the confusion many people have about Pluto's planetary status, setting up the central question: Why is Pluto not a planet anymore?
Before 2006, school textbooks taught that there were nine planets, with Pluto being the smallest. Pluto was discovered in 1930 by Clyde Tombaugh and was considered a planet for decades.
In August 2006, the International Astronomical Union (IAU) in Paris reclassified Pluto, leading to its removal from the list of planets. This decision caused changes in educational materials worldwide.
According to the IAU, for a celestial body to be a planet, it must: 1) orbit the sun, 2) be spherical in shape, and 3) have cleared its orbital neighborhood of other equivalent or larger celestial bodies.
Pluto fulfills the first two criteria (orbiting the sun and being spherical). However, in the late 1990s, scientists discovered that Pluto had not cleared its orbital path, failing the third criterion. This led to its reclassification as a dwarf planet.
Scientists found other similar celestial bodies in the Kuiper Belt, such as Haumea, Makemake, and Eris (which appeared bigger than Pluto). These discoveries highlighted the need for a clearer definition of a planet, as these objects, like Pluto, did not fit the traditional planetary mold.
The video concludes with fun facts: the name "Pluto" was suggested by an 11-year-old girl named Venetia Burney in 1930, and Pluto is unique for having ice volcanoes and a hidden ocean beneath its icy surface.