How Circumference of Earth was calculated using Stick & its shadow | Eratosthenes | No Shadow day

Описание: #eratosthenes #noshadowday #earth #space
How an historic Greek mathematician calculated the Earth's circumference during zero shadow day. In the mid-twentieth century, we commenced launching satellites into area that could assist us decide the precise circumference of the Earth is 40,075 km. But over 2,000 years, a person calculated the Earth's circumference without leaving Alexandria.That guy turned into Eratosthenes. A Greek mathematician and the head librarian at Alexandria. The story goes like this: One day, Eratosthenes had heard from travelers about a well in Syene (now Aswan, Egypt) with an interesting property: at noon on the summer solstice, which occurs every year, the sun illuminated the entire bottom of this well, without casting any shadows, indicating that the sun was directly overhead. Eratosthenes then measured the angle of a shadow cast by a stick at noon on the summer solstice in Alexandria, and found it made an angle of about 7.2 degrees.He realized that if he knew the distance from Alexandria to Syene, he could easily calculate the circumference of Earth. So Eratosthenes hired professional surveyors trained to walk with equal length steps. They found that Syene lies about 800 km from Alexandria. Eratosthenes then used this to calculate the circumference of the Earth to be about 40,000 km. But Modern day value of earth's circumference is 40,075 km. Only 75 km is the difference between his value and us. And just like that, a man 2200 years ago found the circumference of our entire planet with just a stick and his brain.


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