How the Solar System Was First Measured

Check out my podcasts here: https://pods.to/rationalthinker Support me on Patreon: patreon.com/RationalThinker Johannes Kepler had the relative sizes of the orbits of our planets in the solar system mapped by the 1630s. The shape of the solar system had been known relatively well, but it was a shape without scale. Determining the size of the solar system was a much more challenging problem, mainly because there was no known way to make such a measurement. However, that all changed with the development of parallax and taking advantage of an even more fascinating phenomenon: the transit of Venus. Sources: Cassini, Giovanni & Richer, Jean parallax measurement; general parallax explanation — "Why should you care about the Transit of Venus?" National Air and Space Museum, Smithsonian Institution, June 4, 2012. https://airandspace.si.edu/stories/ed... Cook's 1769 Tahiti observation, Fort Venus, quadrant theft — Bryan, Jennifer. "Transit of Venus 1769." Special Collections & Archives Blog, Nimitz Library, U.S. Naval Academy, June 5, 2019. https://libguides.usna.edu/sca/10536/... Cook, Green, and Maskelyne's Tahitian expedition (detailed) — Orchiston, Wayne. "Cook, Green, Maskelyne and the 1769 Transit of Venus: The Legacy of the Tahitian Observations." Journal of Astronomical History and Heritage, 2017. https://ui.adsabs.harvard.edu/abs/201... Horrocks and Crabtree (1639), Mason and Dixon, Le Gentil, black-drop effect, 1874/1882 transits — Monastersky, Richard. "The Venus Hunters." The Chronicle of Higher Education, 2004. https://web.williams.edu/Astronomy/ec... Le Gentil biography — Ashworth, William B., Jr. "Guillaume-Joseph Le Gentil." Scientist of the Day, Linda Hall Library, September 12, 2017. https://www.lindahall.org/about/news/... Visibility maps for the 1761 and 1769 transits — "The Transits of Venus of 1761 and 1769." Transit of Venus bibliography, Utrecht University. https://webspace.science.uu.nl/~gent0... Aristarchus/Eratosthenes background, Kepler, Horrocks's aim (Venus's diameter vs. distance), planetary distances derived from AU — Mayo, Lou. "The Story of the Transit of Venus." Universe in the Classroom, No. 65, Astronomical Society of the Pacific, Spring 2004. https://astrosociety.org/file_downloa... Comprehensive narrative history — Halley's 1716 paper and quote, Mason and Dixon, Chappe's two expeditions, Le Gentil's full account, Cook's voyage, Hornsby's and Lalande's figures, Encke's 1824 calculation, Harkness and the 1874/1882 transits, radar and modern AU precision — Hudon, Daniel. "A (Not So) Brief History of the Transits of Venus." Journal of the Royal Astronomical Society of Canada, February 2004. https://people.bu.edu/hudon/transit_j...