Everything Everywhere Daily: History, Science, Geography & More How Many Planets Are There?
Jul 28, 2020
Discover the fascinating saga of Pluto's journey from planet to dwarf planet, and the historical context behind this controversial change. Explore how ancient astronomers shaped our understanding of celestial bodies and the word 'planet' itself. Uncover the dynamic evolution of planetary classification, revealing how societal perceptions of our cosmic neighbors have shifted over time. It's a captivating look at how our view of the universe—and our place in it—continues to evolve.
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How Planet Definitions Shifted With Worldview
- Ancient astronomers counted moving lights and included the Sun and Moon as 'planets' because Earth was assumed central.
- The Copernican shift reframed the Earth as a planet and changed the planet count from five/seven to six.
Herschel Mistook Uranus For A Comet
- William Herschel discovered Uranus in 1781 and initially thought it was a comet, not a planet.
- That discovery increased the known planets and expanded telescopic astronomy's reach.
19th Century 'Planet' Rush Became The Asteroid Belt
- Between 1801 and 1807 astronomers discovered Ceres, Pallas, Juno, and Vesta and called them planets at first.
- Later those objects were reclassified as asteroids after many similar small bodies were found sharing the same orbit.