How Man ACTUALLY Proved That The Earth Is (drumroll) “Round!”

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10 Easy Ways To Prove Flat-Earthers Are Flat OUT Wrong! Can you say Eratosthenes?! Contrary to popular American myth that only Columbus thought the Earth was round (and the crazy-pants belief that the Earth is flat that’s resurfaced in recent months), humans have known since around 240 BC that the Earth is indeed round. We need look no further than the moon during a lunar eclipse to see the disc-shaped shadow of the Earth. You skeptics out there might be saying, well, ok it’s not a rectangle, but that round shadow just means we’re living on a flat circle, not a sphere. So, who figured it out, and how!!

Eratosthenes discovered the Earth was round, and performed the first accurate calculation of its size. And he did it all using the Sun. Here’s how, as explained by scienceblogs: “If you follow the Sun’s path through the daytime sky, and you live in the Northern hemisphere, you’ll find that it rises in the eastern part of the sky, rises up to its apex in the south, and then lowers and sets in the west. And it does this every day of the year.

“But it doesn’t take the exact same path every day out of the year; the Sun reaches a much higher point (and shines for more hours during the day) during the summer months, and reaches a significantly lower point (and shines for fewer hours) during the winter.

“In fact, if you charted out the Sun’s path through the daytime sky, you would find that it takes its lowest path (for the fewest number of hours) on the Winter Solstice — usually December 21st — and its highest path (for the greatest number of hours) on the Summer Solstice, usually June 21st.

“If you constructed a camera capable of photographing the Sun’s path through the sky over the course of the year, you would find exactly this: a series of arcs, where the highest, longest arc through the sky was made during the Summer Solstice and the lowest, shortest arc was made during the Winter Solstice.”

The ancient Greek astronomer, Eratosthenes received correspondence pertaining to the summer solstice while living in Alexandria. It said that on the solstice in Syene, “the shadow of someone looking down a deep well would block the reflection of the Sun at noon.” This is because the Sun would be directly overhead at the time, causing a completely vertical object to cast no shadow.

According to scienceblogs, “Eratosthenes knew that this wasn’t the case where he was, in Alexandria. Sure, the Sun came closer to being directly overhead at Noon on the Summer Solstice in Alexandria than at any other time during the year, but vertical objects still cast shadows. And — like any good scientist — Eratosthenes did the experiment. By measuring the length of the shadow cast by a vertical stick during the solstice noon, he could figure out what angle the Sun made with the vertical direction at Alexandria.”

He got the answer 7.2 degrees in Alexandria. Knowing that in Syene, the Sun’s angle made with an identical vertical object was 0 degrees, he sought to determine why the difference was occurring.

He realized that would happen if all of the Sun’s rays were parallel and striking a curved object—in other words, a round Earth.

Then, by determining the distance from Alexandria to Syene, he could figure out the circumference of the Earth.

He found the distance from Syene to Alexandria to be 5,000 stadia, the unit of measurement at the time, corresponding to the length of a stadium. It’s a matter of debate which stadium length Eratosthenes was using—a Greek one or an Egyptian. But either way his results were impressive: a Greek stadium measures 185 meters, which would put the circumference of the Earth of 46,620 kilometers, only about 16% bigger than the actual value. An Egyptian stadium is 157.5 meters, giving a value of 39,375 kilometers, which is off by less than 2% from the actual Earth’s circumference of 40,041 km.

Not too shabby! Now, let’s not undo all the great work of Eratosthenes and others by confusing a belief with actual science.

Source: Scienceblogs

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