Summary of Is Pluto a planet?

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This video provides a brief history of the word "planet" and explains why Pluto was relegated to the asteroid belt. It discusses the history of the word "planet" and how astronomers reclassified the solar system's planets based on their size, distance from the sun, and similarity to other planets.

• 00:00:00 The title of the video is "Is Pluto a planet?" and it discusses the history of the word "planet." The ancient Greeks called Mercury, Venus, Mars, Jupiter, Saturn, the Moon and sun planets, and based on their movements and brightness, these objects were considered planets. However, this definition was limited because the best technology they had at the time couldn't detect differences between the Moon and Saturn. Over time, astronomy improved and the Dutch made the first telescopes that allowed for better observations of the universe. Astronomers then reclassified the solar system's planets based on their size, distance from the sun, and similarity to other planets. Pluto was discovered in 1930 and because it was smaller than most of the other objects in the solar system, it was initially considered to be a planet. However, as observations continued to shrink Pluto's size, it was realized that it is made mostly of ice and it was grouped with other icy objects into the Kuiper belt. This video provides a brief history of the word "planet" and explains why Pluto was relegated to the asteroid belt.