According to pythagoras what was the shape of the earth

Aristotle also believed that the world was spherical, but he used observations to prove that it was true. He pointed out that when the earth casts a shadow on the moon during a lunar eclipse, the shadow is always circular.

Can you think why this proved that the earth was a sphere? Try visualising what the shadow would look like if the earth was a flat disc. What would happen to the shadow if you tilted or rotated the disc in different directions? You could even try this with a lamp in a darkened room and some different shapes to represent the earth. As you can see then, the only shape that would always cast a circular shadow is a sphere.

Aristotle also noticed that people could see different stars and constellations depending on how far north or south they were, so that also suggested that the earth was spherical. If you have seen the film Pirates of the Caribbean: at world's end , where the ship falls off the edge of the world over a giant waterfall, then you will know that a lot of people used to think the earth was flat. Even though astronomers knew that it was round, it didn't convince a lot of ordinary folk who were frightened of sailing too far and falling into oblivion.

Can you think of some reasons why the idea of a flat earth seemed so plausible to so many people? Today we know that the earth is spherical because we have been able to measure its curvature very accurately and even see it from space. Eratosthenes was fascinated with geography and planned to make a map of the entire world. He realized he needed to know the size of Earth.

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 about June 21 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. He realized that if he knew the distance from Alexandria to Syene, he could easily calculate the circumference of Earth.

But in those days it was extremely difficult to determine distance with any accuracy. Some distances between cities were measured by the time it took a camel caravan to travel from one city to the other. But camels have a tendency to wander and to walk at varying speeds. So Eratosthenes hired bematists, professional surveyors trained to walk with equal length steps.

They found that Syene lies about stadia from Alexandria. Eratosthenes then used this to calculate the circumference of the Earth to be about , stadia. Modern scholars disagree about the length of the stadium used by Eratosthenes.

The Earth is now known to measure about 24, miles around the equator, slightly less around the poles. Eratosthenes had made the assumption that the sun was so far away that its rays were essentially parallel, that Alexandria is due north of Syene, and that Syene is exactly on the tropic of cancer. His basic method is sound, and is even used by schoolchildren around the world today. Other resources on Earth Redshift Earth and Space. A selection of diagnostic questions to use remotely with your students whilst teaching about Earth and Space Remote teaching support Time Forces and Motion.

Earth Earth and Space. Demonstration: an experiment carried out by Eratosthenes over years ago. Misconceptions Earth and Space Some students say the Earth is a sphere and we live on the outside of the sphere with people living all over the sphere Number of Resources 1 Number of References 6 Number of Diagnostic Resources 3.

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