{"id":45428,"date":"2023-05-30T07:30:17","date_gmt":"2023-05-30T07:30:17","guid":{"rendered":"https:\/\/www.skyatnightmagazine.com\/?p=118528"},"modified":"2023-05-30T10:32:31","modified_gmt":"2023-05-30T10:32:31","slug":"how-we-discovered-the-true-shape-of-the-earth","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/how-we-discovered-the-true-shape-of-the-earth\/","title":{"rendered":"How we discovered the true shape of the Earth"},"content":{"rendered":"

Is Earth like an upright egg, or a squashed spheroid? It would take an epic 18th century expedition to finally find out. <\/p>

By Ezzy Pearson\n \t\t<\/p>

Published: Tuesday, 30 May 2023 at 12:00 am<\/p>

\n\n

Earth is round. The vast majority of people know and accept this, and there are indeed ways to prove that Earth is round, not flat<\/a>.<\/p>\n

But Earth isn\u2019t completely round: the speed at which our planet spins makes it more of a\u00a0 squashed shape, with the north and south poles slightly flattened.<\/p>\n

You can find out more about this in our video demo below.<\/p>\n

<\/p>\n<h2>Discovering the true shape of Earth<\/strong><\/h2>\nThe ancient Greeks believed that circles and spheres were the perfect shapes, a belief which carried over into Old World science.<\/p>\nThis idea wasn\u2019t challenged until the Enlightenment era, leading to two new theories about our planet\u2019s shape.<\/p>\nFrench philosopher Ren\u00e9 Descartes\u2019s theories about vortices in the ether suggested Earth was shaped like an upright egg, stretched towards the poles.<\/p>\nMeanwhile, <a href=\""https:\/\/www.skyatnightmagazine.com\/space-science\/isaac-newton\/"\">Isaac Newton<\/a>\u2019s theory of <a href=\""https:\/\/www.skyatnightmagazine.com\/space-science\/what-is-gravity-facts-about-force\/"\">gravity<\/a> suggested Earth\u2019s spin would make the equator bulge out, while flattening the poles.<\/p>\nKnowing which was true would greatly increase the precision of naval navigation, so the French and Spanish governments sponsored two expeditions to solve the issue.<\/span><\/p>\n<div class=\""image-handler__container\" image-handler__container--full=\"\" style=\""padding-bottom:\" calc=\"\"> <picture><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=300%2C193,\" https:=\"\" type=\""image\/webp"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=300%2C193,\" https:=\"\" type=\""image\/jpeg"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=355%2C228,\" https:=\"\" type=\""image\/webp"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=355%2C228,\" https:=\"\" type=\""image\/jpeg"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=405%2C260,\" https:=\"\" type=\""image\/webp"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=405%2C260,\" https:=\"\" type=\""image\/jpeg"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=554%2C356,\" https:=\"\" type=\""image\/webp"\"><source media=\""(max-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=554%2C356,\" https:=\"\" type=\""image\/jpeg"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=620%2C398"\" type=\""image\/webp"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=620%2C398"\" type=\""image\/jpeg"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=408%2C262,\" https:=\"\" type=\""image\/webp"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=408%2C262,\" https:=\"\" type=\""image\/jpeg"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?webp=true&quality=90&resize=556%2C357,\" https:=\"\" type=\""image\/webp"\"><source media=\""(min-width:\" data-srcset=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=556%2C357,\" https:=\"\" type=\""image\/jpeg"\"><img class=\""wp-image-118531\" align=\"\" size-full=\"\" image-handler__image=\"\" image-handler__image--full=\"\" no-wrap=\"\" js-lazyload=\"\" data-src=\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2023\/05\/C0018594-Measuringadegreeofthemeridian1736-a7823e7-e1683628154850.jpg?quality=90&resize=620%2C398"\" width=\""1200"\" height=\""771"\" alt=\"""\" title=\"""\"\/><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div><div class=\""caption-hold"\"><figcaption class=\""wp-caption-text"\"> Expeditions to the equator (above left) and to Lapland (right) proved that Newton was spot-on with his 1687 theory that Earth is slightly flatter towards the poles. Credit: Sheila Terry \/ Science Photo Library<\/span><\/figcaption><\/div>\nOne would head to Lapland near the Arctic circle, the other to the equator, to measure the length of one degree of latitude.<\/span><\/p>\nIf Lapland was longer, Decartes was correct; if it was the equator, then it was Newton. <\/span><\/p>\nIn 1735, an expedition set sail for the Andes in modern-day Equador.<\/p>\nBad planning, extreme weather, volcanic eruptions and a leader who spent much of the team\u2019s money buying diamonds for his mistress meant it was a decade before any crew member came home.<\/p>\nBy then, the Lapland expedition had long since returned, compared their own measurements to those taken in Paris, and proved that Newton\u2019s idea was correct.<\/p>\nThis article originally appeared in the May 2023 issue of <\/strong><\/em>BBC Sky at Night Magazine<\/strong>.<\/strong><\/em><\/p> <\/body><\/html>\n<hr class=\"no-tts wp-block-separator\"\/>","protected":false},"excerpt":{"rendered":" Is Earth like an upright egg, or a squashed spheroid? 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