Who used the shadow of the midday sun to prove that the earth is round? 20

The concept that the Earth is spherical was first introduced BC.

The ancient Greek philosopher Pythagoras in the fifth and sixth centuries proposed it. But this belief of his was only based on his belief that the sphere was the most perfect of all geometric forms, and not on the basis of any objective fact. Later, Aristotle gave the first scientific evidence that the earth was spherical based on the fact that the shadow of the moon appeared on the surface of the moon at the time of the lunar eclipse was circular.

In the 3rd century B.C., 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, astronomers from the Tang Dynasty presided over the national astronomical geodetic survey, using the height of the North Pole and the length of the summer day to calculate the length of the meridian and the circumference of the earth. The circumnavigation of the globe in 1622 led by the Portuguese navigator Ferdinand Magellan proved that the Earth is indeed spherical.

At the end of the 17th century, Newton studied the influence of the Earth's rotation on the shape of the Earth, and believed that the Earth should be an ellipsoid with a slightly uplifted equator and slightly flattened poles. In 1733, the Paris Observatory sent two expeditions to Peru at 2° south latitude and La Pulin at 66° north latitude to carry out geodetic surveys, and the results confirmed Newton's speculation.

After the 60s of the 20th century, artificial satellites were launched into space, adding new means to geodesy. The average equatorial radius of the earth has been accurately measured to be kilometers, the polar radius is kilometers, the equatorial circumference and meridian circumference are 40,075 kilometers and 39,941 kilometers respectively, the Arctic region is about meters higher, and the Antarctic region is 24-3 meters lower. Some people say that the earth is like a big duck pear lying upside down.

Actually, these irregular parts of the earth are insignificant to the earth. Judging from the Earth** photographed by an artificial earth satellite, it is more like a standard round ball.

Eratosini of Ancient Greece.

Select d shadow facing north, indicating that the sun shines from the south, the northernmost point of the direct sun point is the Tropic of Cancer, for the area north of the Tropic of Cancer, the sun always shines from the south, and there is a polar night phenomenon in the Arctic Circle, which means that there may be no shadow at noon. So the answer is D

Between the Tropic of Cancer and the Arctic Circle.

Let's be in this position, the shadow is facing north, and the position of the southern hemisphere is opposite, the shadow is facing north of the North and South Pole Circle, and the shadow is still facing south, but it is night for half of the year, and day for half of the year, and there is no shadow for many times.

dBetween the Tropic of Cancer and the Arctic Circle.

Because the Sun moves between the Tropic of Cancer and between the Tropic of Cancer and the Arctic Circle, the Sun is always to the south of them, so the shadow of the Sun at noon every day of the year always faces north.

Pick B.

The sun always moves between the Tropic of Cancer, so the objects south of the Tropic of Cancer will always face south, and the objects north of the Tropic of Cancer will always face north.

b.Tropic of Cancer to the Arctic Circle.

the area between the equator and the Tropic of Capricorn, sometimes with a shadow facing south at noon; In areas north of the Arctic Circle, there are sometimes polar nights, and there is no shadow at noon, so only B can be chosen.

b Because at the Tropic of Cancer to the South Pole, the shadow faces south at noon, while the equator to the Tropic of Cancer is in the southward direction in the summer.

Select d shadow facing north, indicating that the sun shines from the south, the northernmost point of the direct sun point is the Tropic of Cancer, for the area north of the Tropic of Cancer, the sun always shines from the south, and there is a polar night phenomenon in the Arctic Circle, which means that there may be no shadow at noon. So the answer is D

The zone where the noonday shadow on Earth always points north is from north of the Tropic of Cancer to south of the Arctic Circle.

The noon figure on Earth during the year is sometimes at the feet, sometimes pointing south, and sometimes pointing north, the area south of the Tropic of Cancer to the north of the Tropic of Capricorn.

On the Tropic of Cancer, there is a noon figure at the foot once a year, appearing on the summer solstice.

At noon (note) the shadow always points north of the Tropic of Cancer.

The shadow always pointing north is the South Pole.

Sometimes at the foot, sometimes south, sometimes north is between the Tropic of Capricorn.

The Tropic of Cancer is only once a year at the feet, on the summer solstice.

North of the Arctic Circle.

Tropic of Cancer.

Once, the summer solstice.

The answers are: Antarctica;

between the Tropic of Cancer;

Once, it occurred on the summer solstice.

At the South Pole, as long as there is a shadow, the shadow must face north.

South of the Antarctic Circle! The Sun does not go to the !! within the Antarctic Circle.

North of the Tropic of Cancer.

I was surprised that the first three floors actually said that the Antarctic Circle omg!

A place south of the Tropic of Cancer to north of the Antarctic Circle.

South of the Tropic of Capricorn is not difficult to understand.

North of the Antarctic Circle, it is mainly due to the fact that there are polar nights in the Antarctic Circle that vary for half a year, and there are no shadows.

The place south of the Tropic of Cancer to the north of the Antarctic Circle because the direct sunlight is between the Tropic of Cancer.

A place south of the Tropic of Cancer on Earth.

The patriarchal system is the basis of the feudal system, and the feudal system is the manifestation of the patriarchal system in the political system.

A place south of the Tropic of Cancer on Earth.

The Northern Hemisphere is about north of 31 degrees.

I forgot how many degrees

b。Within this range, the shadow is always facing north.

A: When the Sun is in the Tropic of Cancer, the shadow of the area south of the Tropic of Cancer is facing south.

C: At the North Pole, the shadow always faces south.

D: The reason is the same as A.