Although people in ancient times did not have advanced scientific and technological knowledge, they were also very interested in the universe and the stars. Ancient people often think: what is our world like? What are the stars in the sky? Although the ancients did not have astronomical telescopes and other observation equipment, but through a long time with the naked eye to observe the sky and record, they also had a certain understanding of the sky.
By observing the starry sky, the ancients understood that the celestial bodies were in motion, but they did not know whether the earth was in motion or the stars were in motion. With the rapid development of human civilization, after entering the era of science and technology, we really understand that the earth we live on is just a tiny planet, which revolves around the sun while rotating.
Before human beings walked out of the earth, although we initially knew that the earth rotates and moves around the sun, the feeling and cognition of being on the earth was relatively weak. Only when we really walk out of the earth and stand in space can we really see what the earth looks like, and clearly see that the earth is rotating at a high speed, and it is moving around the sun.
Before human beings realized the Milky way beyond the solar system, we had always thought that the sun was motionless, and so was the whole galaxy. However, with the continuous improvement of observation technology, we finally knew the existence of the Milky way. At that time, we also understood that the solar system was actually in rotation and revolution.
The solar system is about 27000 light-years away from the galactic center. It is located between the human horse arm and the Orion Arm, close to the inside of the Orion Arm. It orbits the Milky way about 250 million years ago. This is a very long time. At this time, many people realize that the universe may not be a static space, and everything in the universe may be in interlocking motion.
If so, around whom is the galaxy moving? Whether it is a celestial body or a galaxy, their revolution is around a huge gravitational source. For example, the largest gravitational source of the solar system is the star sun, so the earth revolves around the sun. The largest gravitational source of the galaxy is the supermassive black hole in the center, so the solar system revolves around the silver center.
So if we want to make the Milky way with a diameter of 100000 light-years revolve, the gravitational source must be too large for us to imagine. What is the revolution of the Milky way? In the past, scientists believed that when the Milky Way rotates around the central black hole, its revolution should also move periodically around a huge gravitational source.
However, a large number of observations later found that the rotation of the Milky way is completely different from the rotation of the sun around the silver center. You should know that the Milky way is already regarded as a relatively large galaxy in the universe, and its mass itself is very, very large. If we want the galaxy to truly revolve around a fixed gravitational source, the mass of this gravitational source is many times larger than that of the galaxy, and such a gravitational source does not seem to exist outside the galaxy.
Therefore, the revolution of the Milky way is more complex, not as regular as the rotation, nor as regular as the motion of the solar system around the galactic center. It is difficult to determine who is moving around whom in the revolution of the galaxy. The motion of the galaxy is the real motion. Unlike the motion of the solar system around the galactic center, it will not change much in a long time.
But the motion of the Milky way is constantly changing position, now in this position, many years later to other places. So scientists have come to a conclusion: the Milky way has a direction of motion, but it does not revolve. The speed of the Milky way has exceeded 600 km / s. if it revolves around a celestial body, but it is not thrown away, and the total mass of the Milky way is as high as 150 billion times that of the sun, what mass of black hole is needed to drag the Milky way and let it revolve around itself?
So there is no such black hole outside the galaxy, its motion mode is rotation at the same time in a certain direction. In 1988, the international astronomical research group “Seven Samurai” analyzed the motions of 400 nearby elliptical galaxies and found that the Milky way and millions of nearby galaxies were moving towards an unknown gravitational source in the direction of Centaurus at a speed of more than 600 km to 1000 km per second.
This is the beginning and end of the discovery of what was later known as the giant lead source. The specific location is 307 degrees of the silver longitude and 9 degrees of the silver latitude. It is about 150-250 million light years away from the Milky way. According to the estimation, the mass is about 3-5.4 × 10 ^ 16 times. Because it is located in the direction of the silver plate and is covered by a lot of dust, the range of error in the estimation of distance accuracy is very large.
It’s not clear what this huge unknown gravitational source is. We should know that the ability to drag a large number of galaxies like the Milky way towards it shows that the source of gravity is extraordinary. When scientists found that this unknown huge gravitational source was dragging the galaxy closer and closer, many people were very worried that one day the galaxy would completely fall into this gravitational source.
You know, our gravitational source is still in an unknown state. If it is an unimaginable black hole, and if it runs into the pit one day, isn’t the whole galaxy going to die? So does that worry exist? In fact, as long as we calculate the velocity of the giant source away from us according to the Hubble constant, we can understand.
We need to understand that because the universe has been expanding rapidly, this giant source of attraction is also moving away from the Milky way with the expansion of the universe. If the speed of the Milky Way approaching is greater than that of the gravitational source, the Milky way will bump into it sooner or later. But if the gravitational source’s away speed is greater than the galaxy’s close speed, there will never be any contact between them.
The Hubble constant is 67.15 km / s, which is the speed increasing every 3.26 million light years. The distance between the giant gravitation source and the Milky way is 150 to 250 million light years, and our lower limit is 150 million light years. Finally, v = 150 million light years / 3.26 million light years × 67.15 km / S = 3089.72 km / s.
According to the calculation, we know that the fastest galaxy is only 1000 km / s close to the giant gravitation source, which can not keep up with the speed of the giant gravitation source far away from us. Of course, this is not the speed of the giant gravitation source itself, but the additional speed of the expansion of the universe. Here, we would like to thank the expansion of the universe. Without it, the galaxy may really be finished in the future. The galaxy is finished, and it is difficult for human beings to survive.
Although the galaxy is not in danger of hitting the gravitational source, its own crisis has not been completely solved. We need to know that the Milky way and several other galaxies have been entangled and intertwined, and they are also close to each other when they are moving. For example, the Magellanic and Andromeda galaxies around the Milky way are always getting closer to each other.
Earlier scientists thought that large and Small Magellanic galaxies might be engulfed by the Milky way, but the latest observations suggest that Large Magellanic galaxies might first escape the Milky way and then merge with Andromeda. The merger of Andromeda and the Milky way is a fact generally accepted by the scientific community, and the time of their merger may begin in 4 billion years.
Although scientists have always stressed that the merger of the two large galaxies is very safe and there will not be much noise, these are only our simulation experiments and conjectures. It is still unknown what will happen to the merger of the two major galaxies in four billion years. We also need to get more data by observing the merging of other galaxies in the universe.
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