Uploaded January 2019 | Updated September 2026, 2 weeks ago

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In 2006, Pluto was reclassified as a “dwarf planet.” This had two main effects on our solar system: it reduced the number of recognized planets to eight, and left many Earthlings very sad. But Pluto’s demotion reignited a conversation that scientists have had since Neptune’s discovery: is there a “Planet X” orbiting the Sun that we don’t yet know about?

Learn more: popsci.com/solar-system-next-planet-x/?utm_medium=social&utm_source=youtube

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Producer/Video by: Jason Lederman

Narrator: Eleanor Cummins
Music: APM Music

Special Thanks: Br. Guy Consolmagno, IAU
Media: NASA, JPL, JPL-Caltech, ESO, Prelinger Archives, IAU, Pexels, Getty Museum, FreeSound.org, Buena Vista Pictures (The Hitchhiker’s Guide to the Galaxy)

Additional Media:
ESA/Rosetta/NAVCAM (photojournal.jpl.nasa.gov/catalog/PIA19687)
NASA/Ames/JPL-Caltech (images.nasa.gov/details-PIA13833.html)
NASA/JPL-Caltech/Univ. of Arizona (images.nasa.gov/details-PIA22051.html)
NASA/JPL-Caltech (images.nasa.gov/details-PIA22098.html)
depositphotos.com/39943223/stock-photo-mercury-statue.html
depositphotos.com/82803476/stock-photo-the-goddess-of-love-aphrodite.html
depositphotos.com/67151135/stock-photo-god-of-war-mars-ares.html
depositphotos.com/82416024/stock-photo-portrait-of-zeus.html
depositphotos.com/223348754/stock-photo-god-saturn-statue-summer-garden.html

CC-BY-4.0:
NASA/LROC/M.Kornmesser (eso.org/public/videos/moon_big_4k/)
ESO (eso.org/public/videos/eso1134a/)
NASA/ESA/M.Kornmesser (eso.org/public/videos/earth_2015_4k/)

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