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universe

In the following century and a half, H. Shapley discovered that the sun is not at the center of the Milky Way, J. H. Oort discovered the rotation and spiral arms of the Milky Way, and many people determined the diameter and thickness of the Milky Way, and the scientific concept of the Milky Way was finally established.

In the middle of the 18th century, Kant and others also proposed that there are countless celestial systems like the Milky Way in the entire universe.

By 1924, E.P. Hubble had confirmed the existence of extragalactic galaxies by measuring the distance of the Andromeda galaxy using the Cepheid parallax method.

Geometry editing

Diameter and age

The latest research suggests that the diameter of the universe could reach 92 billion light-years or more. [29]

The current observable age of the universe is about 13.82 billion years. [30]

shape

The temperature of the cosmic microwave background is high at one end, suggesting a curved shape

The temperature of the cosmic microwave background is high at one end, suggesting a curved shape

The current theory of the universe, which suggests that the universe may be a sphere, resembling a saddle-like negative curved shape, is derived from the Big Bang theory, in which the entire universe is shaped like a blown balloon, and we live on the "surface" of the universe. [32]

At the same time, scientists also believe that the universe is flat, and according to NASA surveys, the universe may be flat, and the 2013 survey found that if the universe was flat, then the error was only 0.4%. [33]

Stephen Hawking said that the shape of our universe could be an incredible geometry, closer to surrealist art, like the Dutch artist Moritz Kneeris Eschertron

Galaxy

Galaxy

made the same graphics.

Hawking's idea is based on string theory, which is still hypothetical and has not yet been tested. If we use language to describe the shape of the universe, it should be that the whole presents a multi-mosaic pattern, with infinitely repeated distorted surfaces and curved surfaces

The interlocking interlocks, such as the "Circular Limit IV" pattern created by Cornelius Escher, and the "Smith Circle" created by the American engineer P.H. Smith, embody the concept of hyperbolic space, which is a non-Euclidean geometric spatial form.

[35]

Hierarchy

Contemporary astronomical research shows that the universe has a hierarchical structure,

The two galaxies that are about to collide are NGC470 and NGC474

The two galaxies that are about to collide are NGC470 and NGC474

A celestial system that is constantly expanding, diverse, and constantly moving and developing.

Planets, asteroids, comets, and meteoroids all orbit around the central celestial body, the Sun, making up the solar system.

There are other planetary systems outside the solar system as well. About 250 billion sun-like stars and interstellar matter make up the Milky Way, an even larger celestial system. The Milky Way is about 100,000 light-years in diameter, and the Sun is located in one of the spiral arms of the Milky Way, about 30,000 meters from the galactic center

Light-year.

There are many similar celestial systems outside the Milky Way, called extragalactic galaxies, often referred to simply as galaxies. One billion galaxies have been observed so far.

Galaxies are clustered into large and small groups, called galaxy clusters. On average, each galaxy cluster has about 100 galaxies with a diameter of tens of millions of light-years. Tens of thousands of galaxy clusters have been discovered. A small cluster of about 40 galaxies, including the Milky Way, is called

Local group of galaxies.

Jet flow triggered by a supermassive black hole at the center of the elliptical galaxy Hercules A

Jet flow triggered by a supermassive black hole at the center of the elliptical galaxy Hercules A

A higher-level celestial system formed by several galaxy clusters clustered together is called a supercluster. Superclusters tend to have an elongated shape, with diameters of hundreds of millions of light-years. Usually there are only a few superclusters of galaxies in the supercluster, and only a few superclusters are embraced

There are dozens of galaxy clusters.

The supercluster of galaxies formed by the local group of galaxies and about 50 nearby clusters is called the local supercluster.

Classification of galaxies

According to the sequence number that can reflect the development state of galaxies, galaxies can be roughly divided into five types: elliptical galaxies, lens galaxies, spiral galaxies, barred spiral galaxies and irregular galaxies. [38]

Solar system celestial bodies

The mass of the Sun accounts for 99.8% of the total mass of the solar system, and it will, with its own strong gravitational pull

Photos of solar storms published by NASA

Photos of solar storms published by NASA

All the celestial bodies in the solar system are firmly attracted to it, making them revolve around itself in an orderly and orderly manner. At the same time, the Sun, as an ordinary star, leads its members to move around the center of the Milky Way for eternity. [40]

The radius of the Sun is 696,000 km, the mass is 1.989×10^33 grams, the core temperature is about 15000000 K, and the age is 5 billion years. [41] If a person were to stand on the surface of the Sun, he would weigh 20 times as much as the Earth. [42] Modern

Based on observational data and theoretical calculations, the nebula hypothesis proposes that the primordial nebula of the solar system is a small cloud of massive interstellar cloud disintegration, which is rotating at the beginning and shrinking under its own gravitational attraction, forming the sun in the center and evolving into a nebula disk on the outside

, the nebula disk later forms planets. At present, there are different schools of thought in the modern nebula theory, and there are still many differences between these schools, which need to be further studied and confirmed. [43]

Venus is the second planet from the Sun and is second only to the Moon in its night sky. [44] There is no water on Venus, there is a severe lack of oxygen in the atmosphere, carbon dioxide accounts for more than 97%, there is a cloud of concentrated sulfuric acid in the air that is 20 to 30 kilometers thick, and the ground temperature is never good

Below 400°C, it is a veritable "purgatory"-like world. The atmospheric pressure on the surface of Venus is 90 times that of the Earth, which is equivalent to the pressure in the Earth's oceans at a depth of 900 meters. The atmosphere of Venus is mainly composed of greenhouse gases such as carbon dioxide, runaway greenhouses

effect, is the main cause of Venus's extreme climate. Since Venus does not have the intrinsic magnetosphere protection, the huge energy released by the magnetic field reconnection in the magnetosphere is induced, which causes the atmosphere of Venus to escape at an accelerated rate after being heated. The scientific community believes that the escape of the atmosphere on Venus,

It is responsible for the lack of water on Venus and the dense atmosphere rich in carbon dioxide, which leads to a severe greenhouse effect. [45]

Jupiter is the fifth planet from the Sun and is the largest planet, more than all other planets

From ancient times to modern times

The ancient Chinese once put forward the theory of covering the sky and the theory of Hun Tian, and there was Chang'e among the people during the Spring and Autumn Period and the Warring States Period

American artist Pablo Carlos Budassi painted the entire universe

American artist Pablo Carlos Budassi painted the entire universe

In the legend of the moon, the Han Dynasty scholar Zhang Heng also put forward the concept of an infinite universe of "the surface of the universe is infinite, and the end of the universe is infinite". [12] According to the Hun Tian theory, the shape of heaven and earth is like an egg, and the relationship between heaven and earth is like an egg shell wrapped in egg yolk. Zhang Heng thinks that Hun Tian said

It is more in line with the actual observation. [13]

In the 7th century BC, the Babylonians believed that the heavens and the earth were arched, that the earth was surrounded by the sea, and that in its center were high mountains.

The ancient Egyptians imagined the universe as a big box with the sky as the lid and the earth as the bottom, with the Nile River in the center of the earth.

The ancient Jews believed that the earth was the center of the universe, surrounded by a circle of planets, and beyond that, the rest of the celestial bodies were scattered. There is a stationary celestial sphere, and within it, the planets are in their own places, and they are constantly rotating. [14]

The Earth turned out to be spherical

It was the ancient Greeks who first recognized that the earth was spherical. [15] In the 6th century BC, Pythagoras proceeded from the aesthetic concept of the most beautiful three-dimensional figure to be spherical, and advocated that the celestial bodies and the earth were spherical. [16] This notion came later

Inherited by many ancient Greek scholars, it is confirmed by Magellan's circumnavigation of the world in the early 17th century. [17-18]

Geocentrism, heliocentrism, and the law of gravitation

In the 2nd century AD, C. Ptolemy proposed the geocentric theory of the world's first model of planetary systems.

Schematic diagram of Ptolemy's geocentrism

Schematic diagram of Ptolemy's geocentrism

The Earth is at the center of the universe and is stationary. From the Earth outward, there are the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn, orbiting the Earth in their own circular orbits. To illustrate the unevenness of planetary motion, the planets are proposed in this round

It revolves around its center, while the center of the wheel revolves around the earth along the wheel. [20]

In 1543, N. Copernicus's Treatise on the Movement of the Celestial Sphere formally put forward the "heliocentric theory",[21] which held that the sun is the center of the planetary system and that all planets revolve around the sun. The Earth is also a planet that rotates like a spinning top on it, one

The plane, in turn, revolves around the sun like other planets. In medieval Europe, Ptolemy's geocentric theory was dominant because it met the needs of theocratic theory. In order to defend heliocentrism, many people with lofty ideals and dark theocratic ruling forces

Fought one after the other, and paid the price of blood. [22] (To be continued.) )