Is the earth round Why is it called the earth

Why is the Earth round?

The Earth is a sphere, but due to gravity, it is not a perfect sphere, and the equator bulges outwards to form a "spare tire" structure. In fact, the polar radius of the Earth is kilometers, while the radius of the equator is kilometers.

First of all, whether the earth is round or not has little to do with the atmosphere, and as long as the planet is large enough, it is basically spherical.

The main reason is that under the action of gravitation, the gravitational field generated by the force originates from the center of the planet, and under the action of this gravitational field, all matter will have a tendency to pull inward, and the huge mass of the planet itself plus the heat generated by the radioactive elements inside makes it behave like a liquid state, giving in to the gravitational action from the center of gravity, because the shape of the sphere is the most isotropic and stable, so it forms a circle. This process can generally be referred to as equalization adjustment. Moreover, the earth and other stars have both revolution and rotation, and the centrifugal force of rotation shapes it into a spherical shape.

In the early days of Earth's formation, it was a liquid, rocky planet. It took a long time to evolve to become our home.

In the process of evolution, various substances slowly precipitate and stratify according to different densities, and dozens of kilometers below the earth under our feet slowly change from solid to liquid, and the layers of these liquid rocks are thousands of kilometers thick, to some extent, it can be said that the earth is a liquid rock planet.

The subject's use of balloons as an analogy should not be appropriate, first of all, the mass volume is too small to be compared with the planet, and secondly, the direction of the force is uneven, mainly due to gravity. You can see that in the absence of gravity, liquid matter generally becomes spherical automatically!

In addition, the Earth's shape is not perfectly spherical, and its equatorial radius is 1,000 kilometers under the influence of rotation, while the polar radius is 1,000 kilometers, which is still more than 20 kilometers away, so it is a little flattened ellipsoid.

The Earth is a sphere, but due to gravity, it is not a perfect sphere, and the equator bulges outwards to form a "spare tire" structure. In fact, the polar radius of the Earth is kilometers, while the radius of the equator is kilometers.

The Earth is not a perfectly circular sphere, but a rotating sphere with slightly flattened poles and a convex equator.

The so-called spheroid is formed by the rotation of a warp coil around the earth's axis. All the warp coils are equal ellipses, while the equator and all the weft coils are perfect circles. In order to process the results of geodetic surveys, a spheroid that is close to the size and shape of the earth is used and its relationship with the origin of the earth is determined, which is called a reference ellipsoid.

In the nineteenth century, through precise gravitational and geodetic surveys, it was further discovered that the equator is not a perfect circle, but an ellipse, and the length of the diameter is also different. In this way, there are three axes of unequal length from the center of the earth to the surface of the earth, so the shape of the earth is represented by a triaxial spheroid in surveying.

Since then, it has been found that the north and south hemispheres of the earth are asymmetrical, the south pole is closer to the center of the earth than the north pole, and the north pole protrudes by meters, and the south pole recesses meters; It is also concave at latitude 45 north and uplifted at latitude 45 south. This shape is compared to the reference ellipsoid, and the earth is a bit like a pear, so the name "pear-shaped earth" appears in surveying. In short, the shape of the earth is very irregular and cannot be represented by simple geometric shapes.

More precisely, the Earth has a unique terrestrial shape.

Human understanding of the shape of the earth has gradually improved with the development of science and technology. Circular spheres, spheroids, triaxial spheroids, and earth shapes can be said to be approximate to the true shape of the earth. In turn, the shape of the earth needs to be simplified to varying degrees in the struggle for production and in scientific practice.

For example, when making a globe or making a global map, the earth must be seen as a sphere; When surveying large-scale topographic maps, the Earth must be treated as a regular reference ellipsoid; When launching an artificial object and calculating its orbit, it is necessary to calculate the flattening of the equator and the deviation of the reference ellipsoid from each place more accurately.

Therefore, the shape of the earth cannot be represented by a certain geometric shape, and it should be called strictly an earth shape.

Why is the Earth round?

Earth is one of the eight planets in the solar system, the third planet in order of near and far from the sun, and it is also the terrestrial planet with the largest diameter, mass and density in the solar system.

Why is the earth round?

The Earth is a sphere, but due to gravity, it is not a perfect sphere, and the equator bulges outwards to form a "spare tire" structure. In fact, the polar radius of the Earth is kilometers, while the radius of the equator is kilometers.

In fact, not only the earth is round, but every planet is round, why is that?

I think this only shows that the earth must have undergone a process of change from liquid to solid in the process of formation. Perhaps the Earth was also a small sun when it first formed, like the sun we see today, capable of emitting light and heat, and because of its small size (relative to the sun), it would take many billions of years (billions?) Billion?

Three billion? Nobody knows) its thermonuclear reaction has been aborted, and it can no longer emit light and heat, but the temperature on its surface is still very high, all red hot magma, and the action of gravity makes the liquid earth tend to be spherical (isn't this the case with the current sea level of our earth?). ）。

The centrifugal force generated by the rotation of the Earth makes the diameter of the equator slightly larger than the diameter of the north and south poles (kilometer radius of the equator, kilometer radius of the polar axis), which is also consistent with the facts. Later, the temperature of the earth decreased, and the surface slowly became solid (which is also consistent with the red-hot magma in the interior of the earth), and then because of the movement of the earth's crust, it became what we see now, but in general it was spherical. That's why the earth is round.

At the same time, it is also the reason why all the planets in the universe are round.

Of course, it cannot be said that the earth is purely round, but slightly flattened.

Landlord. Hello. First of all, the earth is a three-dimensional structure, and "circle" describes a flat figure, so it seems a bit inappropriate to use "circle" to describe the earth.

The earth is an irregular sphere with slightly flattened poles and slightly bulging equators, and as for why this is so, it has to do with the formation of the earth, and I won't go into it here. If you still have questions, please continue to ask, I hope to adopt!

The Earth can be seen approximately as spherical.

In fact, the Earth's equatorial radius is slightly larger than the radius of the poles.

The Earth is not a positive sphere, but an irregular sphere with slightly flattened poles and a slightly bulging equator.

is an approximate sphere.

The Earth is a sphere, but due to gravity, it is not a perfect sphere, and the equator bulges outwards to form a "spare tire" structure. In fact, the polar radius of the Earth is kilometers, while the radius of the equator is kilometers.

Why is the Earth round?

I'm sure you're not round, it's a bit oval, long on the north and south sides.

It is an irregular spheroid with a slightly bulging equator and slightly flattened poles.

The Earth is a sphere, but due to gravity, it is not a perfect sphere, and the equator bulges outwards to form a "spare tire" structure. In fact, the polar radius of the Earth is kilometers, while the radius of the equator is kilometers.