When did the Chinese know that the earth was round?

The story of the opposite direction comes from "Warring States Policy Wei Ce", which shows that during the Warring States Period, before 243 BC, the wise sages realized that the earth was round and bravely used actions to prove it. Of course he failed. The saddest thing is that his groundbreaking behavior was interpreted as negative teaching material by later generations from different angles. He was laughed at for two thousand years. Until today, it is time for him to be rehabilitated.

China first knew that the earth was round during the Ming Dynasty. China knew that the earth was round when the Italian missionary Matteo Ricci introduced it to the Chinese after Magellan completed his first circumnavigation of the world.

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The concept that the earth is spherical was first proposed by the ancient Greek philosopher Pythagoras in the fifth and sixth centuries BC. However, his belief was only because he believed that the sphere was in all shapes. The most perfect geometric shape, rather than being derived from any objective facts. Later, Aristotle gave the first scientific evidence that the earth is spherical based on the fact that the shadow of the moon during a lunar eclipse is round. In the 3rd century BC, the ancient Greek astronomer Eratosthenes of Cyrene calculated the circumference of the earth for the first time based on the sunlight hitting the earth at noon and the distance between the two observation sites. In 726 AD, Tang Dynasty in my country The contemporary astronomers and his party presided over the national astronomical geodetic survey, and calculated the length of one degree of the meridian and the circumference of the earth using the height of the North Pole and the length of the summer day. The circumnavigation of the world led by Portuguese navigator Ferdinand Magellan in 1622 proved this The earth is indeed spherical. At the end of the 17th century, Newton studied the impact of the earth's rotation on the shape of the earth and believed that the earth should be an ellipsoid with a slightly raised equator and slightly flattened poles. In 1733, the Paris Observatory sent two expedition teams to the southern latitudes. Peru at 2° and Laplin at 66° north latitude were surveyed, and the results proved Newton’s conjecture.

After the 1960s, artificial satellites were launched into the sky, adding new methods to geodetic measurements. Now It is accurately measured that the average equatorial radius of the Earth is 6378.14 kilometers, the polar radius is 6356.76 kilometers, the equatorial circumference and meridian circumference are 40075 kilometers and 39941 kilometers respectively. The Arctic region is about 18.9 meters higher, and the Antarctic region is lower. 24-3 meters. Some people say that the earth is like a big pear lying upside down. In fact, these irregular parts of the earth are insignificant to the earth. Judging from the photos of the earth taken by artificial earth satellites, it is more like A standard round ball.