Is There a Secret 9th (or 10th?) Planet Full of Aliens?
It‘s Probably (not) Aliens!
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The Search for Planet X
This chapter discusses the search for a mysterious Planet X in the early 20th century, including the failed attempts to find it and the eventual discovery of Pluto. It explores the controversy surrounding Pluto's classification as a planet and the ongoing search for Planet X beyond Pluto.
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Transcript
