The hypothesis that the earth is spherical. They advocate using mathematics to explain the universe, thinking that in all three-dimensional graphics, the sphere
Is the most beautiful. The shape of the universe should be spherical, and all celestial bodies in the universe, including the earth, should be
It should be spherical. It took Aristotle, a famous scientist and philosopher in ancient Greece 100 years to visit the earth for the first time.
Prove that the earth is spherical. He observed the celestial phenomena from the projection of the earth on the moon during the eclipse.
It is inferred that the shape of the earth is spherical. At that time, some people opposed it: if the earth is really
It is spherical. Why don't people who live on the other side of the earth fall into the air below? At that time,
Because people don't understand gravity, it is difficult to answer this question.
Zhang Heng, an astronomer in the Eastern Han Dynasty in China, once said that "the sky is like a chicken, and the ground is like a chicken yellow".
Compare the universe to an egg, and the earth is like the yolk in an egg. This theory is called Huntian theory, which is better than the previous theory of covering the sky.
Great progress has been made.
15 and 16 century's great geographical discoveries, especially1519-1521a ship led by Magellan.
The team successfully sailed around the earth, which provided strong evidence that the earth was spherical. In the late Ming Dynasty,
Western missionaries Matteo Ricci and Tang Ruowang came to China and introduced scientific knowledge such as astronomy, geography and mathematics.
Knowledge, the translated name of "Earth" appeared in China.
So, is the earth a round right sphere? /kloc-at the end of 0/7, British physicist Newton root
According to the theory of gravity he discovered, due to the inertial centrifugal force produced by rotation, the earth's
Matter moves in the equatorial direction, so he came to the conclusion that the earth should have an equatorial radius greater than the polar radius.
Flat sphere. However, according to their meridian survey, the faction headed by Cassini, director of the Paris Observatory,
According to inaccurate data, when the earth revolves around the sun, it should extend to the poles, and it is a long ball, not a flat ball.
Ball. This argument lasted for half a century. Voltaire, a French enlightenment thinker, argued about the shape of the earth.
Once said: "In London, it is considered an orange, but in Paris, it is imagined as a watermelon." Until 18.
In 1930s, the French Academy of Sciences sent two expeditions, one to Lapland near the Arctic Circle and the other to Lapland.
Peru, near the equator in South America, measured the meridian length between the two places, but found that Cassini's measurement results were as follows
Wrong, and Newton's inference is correct.
With the continuous progress of measurement technology, especially the use of artificial earth satellites, earth measurement is now
The equatorial radius is 6378 140m and the polar radius is 6356755m. The difference between them is 2 1385m, and its flatness is
1/298.2。 In this respect, the earth is much more round than oranges.
In addition, people also found from the measurement that the equator of the earth is not a perfect circle, but is similar to an ellipse, which is the largest.
The radius differs from the minimum radius by more than 200 meters. It is also found that the northern hemisphere of the earth is thinner than the southern hemisphere; Arctic region
The geoid (mean sea level) in this area is about 10 meter higher than that in the reference oblate sphere and Antarctic area.
It should be recessed about 30 meters. So some people compare the shape of the earth to a pear and describe the globe as a pear.
Body.
In fact, the earth is neither like an orange nor a pear, but a sphere with its own unique shape.
If this huge earth is shrunk into a globe with a diameter of 1 m, the equatorial radius is only polar.
The radius is greater than 1mm, which is a subtle difference that cannot be expressed on the globe, so we use it.
The globe is still round.
Chen ershou