Carl Sagan explains how Eratosthenes calculated circumference of the Earth

[runnergo]

Carl is one of those guys that would have been perfect to be the spokesperson for the entire human race if aliens ever showed up and wanted to talk to us.

[maggs]

Eratosthenese had this fugured out in 200 BC and people today still think the earth is flat. Its as if some people strive to be idiots and devote their lives to this craft

[marta]

Eratosthenes' experiment was so pure, easy to conduct and explain... and above all it was beautiful. BEAUTIFUL!

[carolynnaayem]

Carl, we miss you so much. The people of the world need your wisdom right now.

[maliknaumann]

The folks disliking this video are clearly flat earthers

[ohhdini]

crazy that in this day ppl still spend energy arguing the earth is flat

[dond]

Props to the guy who walked 800 kms and got the measurement correct.

[philosaplease]

leaning this in astronomy 101 was mind-blowing. sadly, posting it on flat-earth/Q/other conspiracy boards and videos is not likely to help any of those lost souls. you can use logic/reason to dissuade someone from a position they didn't use reason or logic to arrive at.

[alessandrofino]

That makes me wonder, although the explanation is very simple, easy to understand. I would never get tired of listening to him. Great Carl Sagan!!! 🙂🌍

[blackholeentry]

In 1980, I toured with a group which went to Egypt, where we repeated Eratothenes famous experiment and came up with very similar calculated a measurement of 7900 miles for the earth's within the ballpark.

[pho.phonic]

I link this video to every flat earther I come across. Belief is the enemy of knowledge, and it is knowledge rather than hate that defeats ignorance.

[thebeast]

The way this man can explain math is beautiful.

[Sheriff_K]

But how did he know the shadows at two different locations at the same time? Did he use an hour glass and timed it on two seperate instances? Or had two people at each point send carrier pidgeons stating the shadow? But he'd had to have KNOWN/suspected the shadows would be different to even go about such an experiment..

[patapata]

this is so B E A U T I F U L, thank you.

[Widderic]

My arguments with flat earthers begin and end the moment I send this video. For idiots of today to unlearn the teachings of 2200 years ago is beyond me. Some people lack any ability to think critically.

[bradsanders]

That's nothing, using only two chopsticks I once successfully calculated what my girlfriend wanted for dinner.

[formerlybernard]

Fucking brilliant. I understand the math now from a simple demonstration in straightforward language. There would be zero chance I would ever come to this original discovery though. Greeks...the mutts nuts.

[nilobeebee]

How did Eratosthenes know in the "SAME INSTANT" that the shadow in Alexandria and the shadow in Syene were different lengths? How?

[BabySagan]

Epic win. Considering reenactment on my channel!

[kevreid]

How did anyone back then know the exact time? Especially in 2 different places at once. If you're 50 miles apart how do you know you're looking at the exact same instance as someone else.