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Carl Sagan - Cosmos - Eratosthenes

carlsagandotcom · 3M views · 2009-04-24 · 6:42

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Overview

A short clip from Carl Sagan's Cosmos in which he explains how Eratosthenes measured the circumference of the Earth using shadows in two Egyptian cities. It is a clear, visual account of an ancient scientific feat.

On Hacker News

HN commenters link it whenever the question of how the Earth's size was first measured comes up, calling it a wonderful explanation.

Recommended by 4 HN people across 4 months · HN mentions 2022–2024

Topics

World historyScientific method & science communicationPure mathematics
Search by tags
eratosthenescarl sagancosmosastronomy historygeometry

What people said

ubutler · 2024-03 · Strong recommendation

One of my favourite episodes of Cosmos centres around Eratosthenes’ calculation of the circumference of the Earth: [VIDEO]

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kemotep · 2023-08 · Recommendation

I heard it was using a military unit’s standard marching pace to calculate the distance. Here is a wonderful video of Carl Sagan explaining it[0]. [0]: [VIDEO]

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jamesgill · 2023-01 · Recommendation

Likely familiar to this crowd, but Carl Sagan's explanation on Cosmos of Eratosthenes' discovery is great: [VIDEO]

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Sources

Video by carlsagandotcom, played through YouTube.

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