How al-Biruni Measured the Whole Earth From One Hill

Around the year 1020, the scholar al-Biruni climbed a hill near Nandana in the Punjab and worked out the size of the Earth from just two numbers: the hill's height and one tiny angle. This is how al-Biruni measured the Earth, step by step, and how it compares with the famous method of Eratosthenes. We also look honestly at how accurate his result really was. Watch next: Why Your $15 Movie Ticket Barely Pays the Theater    • Why Your $15 Movie Ticket Barely Pays the ...   Narration uses synthetic (AI) voices. Chapters 0:00 One hill, one angle, one planet 0:41 Who was al-Biruni? 1:15 Eratosthenes and the two cities 1:59 The horizon drops 2:31 The right triangle 3:28 The formula for the radius 4:05 Measuring a hill you can't reach 4:35 Nandana and the 34 arc-minutes 5:16 How accurate was he, really? 6:13 The horizon holds the answer Sources https://dictionary.obspm.fr/terms/bir... https://mathshistory.st-andrews.ac.uk... https://en.wikipedia.org/wiki/Al-Biruni https://iranicaonline.org/articles/bi... https://mathcs.clarku.edu/~djoyce/ma1... #AlBiruni #IslamicGoldenAge #Science