How an SAT question became a mathematical paradox. Head to https://brilliant.org/veritasium to start your free 30-day trial, and the first 200 people get 20% off an annual premium subscription.

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Huge thanks to Dr. Doug Jungreis for taking the time to speak with us about this SAT question.
Thanks to Stellarium, a wonderful free astronomy simulator – https://ve42.co/Stellarium
Thanks to Newspapers.com, a database of historical newspapers – https://ve42.co/Newspapers

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References:
Summary of this problem by MindYourDecisions –    • Why did everyone miss this SAT Math q...  
More cool math about this problem by Kyle Hill –    • The SAT Question NO ONE Got Right  
Discussion of a solar day by MinutePhysics –    • Why December Has The Longest Days  
Murtagh, J. (2023). The SAT Problem That Everybody Got Wrong. Scientific American – https://ve42.co/SATSciAm
United Press International (1982). Error Found in S.A.T. Question. New York Times – https://ve42.co/SAT-NYT
Yang (2020). What's the hardest SAT math problem that you've seen? Quora – https://ve42.co/SATQuora
Coin rotation paradox via Wikipedia – https://ve42.co/CoinParadox
Simmons, B. (2015). Circle revolutions rolling around another circle. MathStackExchange. – https://ve42.co/CircleRoll
Sidereal time via Wikipedia – https://ve42.co/SiderealWiki
Solar Time vs. Sidereal Time via Las Cumbres Observatory – https://ve42.co/SiderealLCO

Images & Video:
Zotti, G., et al. (2021). The Simulated Sky: Stellarium for Cultural Astronomy Research - https://ve42.co/Stellarium
Newspapers from 1980s - 1990s via Newspapers.com – https://ve42.co/Newspapers
SAT Practice Test via the College Board – https://ve42.co/PracticeSAT
Revolution Definition via NASA – https://ve42.co/RevolutionNASA
Revolution Definition via Merriam-Webster – https://ve42.co/RevolutionWebster
Earth motion animation via NASA – https://ve42.co/OrbitNASA
Satellite animation via NASA – https://ve42.co/SatNASA

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Directed by Emily Zhang
Written by Emily Zhang and Gregor Čavlović
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