Since ancient times, countless people like to look up at the starry sky at night. Looking at the countless stars appearing in the night sky, many people in ancient times would think: What are they?
Because the ancients lacked scientific knowledge and knew nothing about the world beyond the earth, they were full of mysterious curiosity about the sun, moon and countless stars, so there were various myths and legends about stars.
When mankind entered the path of scientific development, in the palace of science, we knew that there was a vaster universe beyond the earth, and the stars we could see at night were basically very far away from us. star.
The stars in the sky are basically stars similar to the sun. If you tell people in ancient times, few people will believe this answer. It is difficult for the ancients to associate the terrible burning sun with those stars. In the eyes of the ancients, the sun is supreme, bringing light and temperature to the world, and bringing hope, but the stars are much weaker. , Completely incomparable with the sun.
But now with a scientific eye, we all know that the sun is insignificant compared to the stars in the sky. Many stars far surpass the sun, such as the largest known star UY Scutum. If it replaces the sun, its orbit can reach the vicinity of Jupiter.
The universe is vast and vast, and stars are the most important celestial bodies in the universe, and they are also a ubiquitous celestial body. Stars rely on their own mass advantages to form a star system, and a large number of star systems form a larger galaxy. Like the Milky Way, is the Milky Way big? From the perspective of the solar system, the Milky Way with a diameter of 100,000 light-years contains approximately 150-400 billion stars.
The solar system is a dust in front of the Milky Way, so how many galaxies are there in the universe? The current data may make people feel hopeless. To figure out how many galaxies there are in the universe, we need to analyze and count them level by level.
The Milky Way is a huge galaxy in front of the solar system, but after you walk out of the Milky Way, you will find that it is nothing at all. There are many large galaxies around the Milky Way. For example, the Andromeda Galaxy, which is 2.54 million light-years away, has a diameter of 220,000 light-years, which is much larger than the Milky Way and contains about 100 billion stars.
In addition to the Andromeda Galaxy, the Milky Way has three neighbors: the Large Magellanic Cloud, which is 163,000 light-years away, the Small Magellanic Cloud, which is 210,000 light-years away, and the Triangulum Galaxy, which is 3 million light-years away.
A large galaxy like the Milky Way is the basic system unit of the universe. It is a huge system composed of many stars, gas, cosmic dust, and various substances under the action of gravity. If the universe is compared to a vast ocean, then each galaxy is equivalent to islands in this ocean.
Many islands in the universe will form a larger structure and a system under the action of stronger gravitation. For example, the Milky Way and about 50 galaxies around it form a group of galaxies, which we call the local group of galaxies. The diameter of the local group of galaxies is about 10 million light-years, which is 100 times the diameter of the Milky Way.
The local galaxy and various other galaxy group structures together form a larger cosmic structure, which we call the Virgo Supercluster, which contains about 2500 galaxies with a diameter of about 65 million light-years. Outside of the Virgo supercluster is the larger Virgo supercluster, which includes at least 100 galaxy groups and galaxy clusters, with a diameter range of about 220 million light-years.
So is the Virgo super galaxy big? Of course not, there is a larger system on it, which we call the Rania Kea supercluster. This is a cosmic system spanning 520 million light-years, including a total of about 100,000 galaxies, including the Virgo Supercluster, the Hydra galaxy cluster, and the Centaurus galaxy cluster.
There are many cosmic superstructures like the Rania Kea super galaxy cluster in the universe, and it forms a huge cosmic fibrous structure together with other nearby super galaxy clusters. These fibrous structures composed of cosmic super galaxy clusters are like a large web. In the center of the big net is the void of the universe, there is nothing.
This fibrous superstructure of the universe, we also call it the Great Wall, is 500 million light-years long, 300 million light-years wide, and has a thickness of 15 million light-years. And the countless tiny sands that make up this Great Wall are large galaxies like the Milky Way.
Such a vast structure of the universe is an eye-opener for people, but when we look farther, you will find that this fibrous large-scale structure is nothing. Standing within the observable universe of 92 billion light-years, it is just a dust. At present, scientists can observe about 125 billion galaxies.
Some people may say that this number is also within a tolerable range, but in fact this is only an observational data based on current human technology. With the continuous advancement of human science and technology and the continuous improvement of observation technology, this number will continue to grow in the future. Even in the large-scale cosmic holes we are currently observing, it is not that there are no galaxies, but they are relatively rare and cannot be discovered by humans’ current observation capabilities.
In addition to the observable universe, there is also an unobservable universe, which may be an even more expansive area. Since the speed of light is fixed, only the speed of light, and the expansion of the universe exceeds the speed of light, the greater the distance between galaxies, the faster the distance between them. When the distance reaches a certain level, the speed of the galaxy away from us will exceed the speed of light. In the outer space of the galaxy, the speed of photons is less than the expansion speed of the universe, and will never reach the earth, and we will not be able to observe the outside. Galaxy space.
It can be seen that the number of star coefficients that may exist outside the observable universe is even greater. It is impossible to observe the space of galaxies beyond the speed of light expansion with current human observation technology. Only in the future when we develop more powerful detection equipment, will it be possible to observe the entire universe regardless of distance. At that time, the number of galaxies in the universe might make us desperate.