Planet Nine: Our Solar System's Missing Planet?

Check out Squarespace: http://squarespace.com/GEOGRAPHICS for 10% off on your first purchase. → Subscribe for new videos two times per week.    / @geographicstravel   Love content? Check out Simon's other YouTube Channels: Biographics:    / @biographics   MegaProjects:    / @megaprojects9649   SideProjects:    / @sideprojects   Casual Criminalist:    / @thecasualcriminalist   Today I Found Out:    / todayifoundout   TopTenz:    / toptenznet   Highlight History:    / @highlighthistory   XPLRD:    / @simonstestchannel   Business Blaze:    / @brainblaze6526   This video is #sponsored by Squarespace. Source/Further reading: BBC, why has no-one seen Planet Nine? https://www.bbc.com/future/article/20... NASA, Planet 9 in-depth:https://solarsystem.nasa.gov/planets/... New Scientist, primordial black hole? https://www.newscientist.com/article/... Smithsonian, Hunt for Planet Nine takes a hit: https://www.smithsonianmag.com/smart-... Scientific American, Planet Nine could be a mirage: https://www.scientificamerican.com/ar... Search for Planet Nine blog: https://findplanetnine.blogspot.com/2... Smithsonian, history of the hunt for Planet X: https://www.smithsonianmag.com/scienc... The search for Trans-Neptunian Worlds: https://solarviews.com/eng/hypothet.h... Nat Geo, the hunt for Planet Vulcan: https://www.nationalgeographic.com/sc... 1870s NYT article on Vulcan’s existence: https://timesmachine.nytimes.com/time... Nibiru myth: https://www.space.com/15551-nibiru.html  Britannica, discovery of Neptune: https://www.britannica.com/place/Nept... Geographics on Pluto:    • Pluto: The Frozen World   Nemesis Star: https://www.space.com/22538-nemesis-s... Sedna orbit and Planet Nine: https://www.astrobio.net/news-exclusi... Mike Brown, Alan Stern rivalry: https://www.theguardian.com/science/2... Finding most-distant ever objects by looking for Planet 9: https://www.sciencealert.com/farfarou... Durer’s Rhino: https://www.historytoday.com/archive/...