The Milky Way is 180,000 light-years in diameter and 1,000 light-years thick, so how much does it weigh?
The entire Milky Way galaxy weighs almost 680 billion suns.
How many stars are there?
There are 100 billion to 400 billion stars, which is a very large range, and there is no way for human beings to understand the universe is limited, so we can only speculate on such a range.
But now scientists can guess a very precise answer: the mass of all stars in the Milky Way is about 96% of the visible matter, leaving 3% of gas and 1% of dust.
As for the invisible matter, it is the invisible dark matter.
There is also the fact that the Milky Way is getting bigger because it is colliding with the Andromeda Galaxy, and scientists believe that in four billion years, the two galaxies will embrace each other and become a whole new galaxy.
Scientists have given this brand new galaxy a good name: the Galactic Andromeda Galaxy.
However, the current Milky Way is only a small galaxy, not very large, it is only one of the fifty members of the local galaxy cluster.
Speaking of which, the question arises, how big is the largest galaxy in the universe?
Today, I will talk about this issue.
Discover the earliest largest galaxies
Before 2022, the largest galaxy known to mankind was a galaxy called IC1101.
Located about 1.045 billion light-years from Earth, the central galaxy of the Abel-2029 cluster is four million light-years in diameter.
This is a huge galaxy that can fit thousands of galaxies into it.
According to scientists, there are 100 trillion stars in the IC1101 galaxy, which contains dark matter equivalent to the mass of 100 trillion suns.
This galaxy far surpasses the Milky Way in terms of the number of stars and the mass of dark matter.
In front of it, the Milky Way is simply a little brother.
The IC1101 galaxy is home to a large number of metal-rich stars.
What are metal-rich stars?
Metal-rich stars, also known as the First Star Family, are young stars that contain very high levels of metal.
The Sun, for example, is a metal-rich star.
Speaking of which, many people will doubt the claim that the sun is a metal-rich star, because in common sense, the sun is actually a balloon, which is composed of helium and hydrogen, how did metal-rich appear?
To explain this, you have to explain the origin of stars.
Many people know that the source of the universe came from a Big Bang, in which not only the universe was born, but also two elements, hydrogen and helium, were born.
And on the basis of hydrogen and helium, the first generation of stars in the universe was born, and these stars lit up the dark universe and brought the first rays of light to this world.
The first generation of stars was born at the very beginning, and there is only hydrogen and helium in the universe, so the body of the first generation of stars is hydrogen and helium.
Stars are not eternal, and there is a moment when life ends.
So over a long period of time, the first generation of stars went to death, and some of them underwent a final explosion in the mode of supernovae, in which an element heavier than helium was born.
In astronomy, these elements, which are heavier than helium, are all called metals (note: not metals in the actual sense). ）
The second generation of stars will reintegrate with hydrogen and helium, as well as metals that the astronomical community would consider, to give birth to entirely new stars.
Of course, the second generation of stars will also come to the end of their lives, and then explode again, producing heavier elements again.
So 9 billion years after the birth of the universe, the third generation of stars re-condensed hydrogen and helium, plus the metal condensed by the previous two generations of stars.
The Sun belongs to the third generation of stars.
Astronomers call the first generation of stars the third family, the second generation of stars the second family, and the third generation of stars the first family.
At present, what scientists most want to find in the vast universe is the third star group, that is, the first generation of stars.
But alas, it was not found, only some second-generation stars were found.
If we can find the first generation of stars, we may be able to solve some of the secrets of the Big Bang, because the first generation of stars contains only the most primitive interstellar matter at the time of the Big Bang.
So in this arrangement, the first generation of stars is metalless, the second generation of stars has trace metals, and the third generation of stars are rich in metals.
In order to quantify metal-rich stars in a standardized manner, scientists use the metallicity of the sun as a reference and regard the ratio of iron to hydrogen as zero, for example, if the ratio of iron to hydrogen in a star is negative, it is a metal-poor star, and if it is positive, it is a metal-rich star.
Now that we know what metal-rich stars are, let's take a look at the IC1101 galaxy, which looks very bright because of the large number of metal-rich stars, like a shell covered in gold.
It is assumed that the center of IC1101's rotation is a black hole with a mass of 40 billion to 100 billion times the mass of the Sun.
The black hole at the galactic center of the Milky Way is only four million times the size of the Sun.
So compared with the two, it can be said that it is a small thing.
Larger galaxies were discovered in 2022
In February 2022, an observatory in Netherlands made a scientific report in which it was mentioned that they had observed the largest galaxy to date.
It is 3 billion light-years from Earth and has a diameter of 16.3 million light-years, which is 160 times the size of the Milky Way and four times the size of the IC1101 galaxy.
This galaxy is called Arcuonius, and its name comes from the giants of ancient Greece mythology.
Speaking of this, I can't help but ask, how can there be such a large galaxy?
In fact, the answer is given above.
The Milky Way is getting bigger now because it's colliding with the Andromeda Galaxy, and in about four billion years, the two galaxies will merge together.
There are many such phenomena in the universe.
For example, in November 2007, United States astronomers used the Spitzer Space Telescope to observe the spectacular collision of four huge galaxies.
Three of these four galaxies are about the size of the Milky Way, and the other is three times the size of the Milky Way, and when they collide, they will eventually create a galaxy ten times the size of the Milky Way.
And this collision will also produce billions of fragments.
What impact does this phenomenon have on the universe?
Think of four trucks full of sand, loaded head-to-head at a high speed, shooting out sand in all directions.
Space is not the Earth, and the sand will continue to move forward until it hits other stars or is captured by a larger star.
So the impact of this impact on the universe will be very large.
Most critically, the cluster of galaxies in which these four galaxies are located is only 5 billion light-years away from Earth.
Then the Alcuonus galaxy has such a huge body, and it is also in this collision, gradually getting larger.
And the fact that he can have such a huge volume can only show that the original Alcuonius galaxy has appeared at the beginning of the universe, so this is an ancient galaxy.
Because it is only through a long period of accumulation that such a huge galaxy can be formed.
Of course, time is one thing, and the super-large black hole at the center of the Alcuonus galaxy is another reason.
Because whether it is a moon or a planet, a planet or a star, a star and a galaxy, they all rely on gravity to maintain their balance with each other.
A massive galaxy won't last long without enough gravity to bind so many stars.
At the center of the Alcuonius galaxy is a super-large black hole.
As for how massive is this super-large black hole? No exact information was found, but comparisons were made.
In the IC1101 galaxy mentioned above, the black hole at the center is 40 billion to 100 billion times the mass of the Sun, and the Alcuonus galaxy is four times the width of the IC1101 galaxy.
And the mass of a black hole is not just a multiple of four.
So the black hole in the Alqueonius galaxy will be even larger.
In fact, in the universe, there are many strange galaxies, let's talk about such a galaxy.
Dark galaxy
What is a Dark Galaxy?
In the eyes of scientists a long time ago, the so-called galaxy should be a structure filled with many stars, which looks like a sparkling light.
But after years of research, scientists discovered a vague galaxy in 2015.
This kind of galaxy is equivalent to removing 99% of the stars in the Milky Way, so it is called a dark galaxy.
When many people hear this, they will feel that this is nothing?
But in the eyes of scientists, it's terrifying.
If a galaxy is not maintained by the gravitational pull of stars, the end result will be light and thin, and the whole will not be tightly integrated.
Then the galaxy will be swallowed up by nearby galaxies with many stars, because it stands to reason that galaxies with stars have a greater gravitational pull.
Moreover, the dark galaxies that scientists have now observed belong to the Comae cluster, in which there are thousands of galaxies, and the whole cluster is quite compact.
In the Comae cluster, forty-seven dark clusters have been discovered.
These dark clusters are all surrounded by giant-like galaxies with stars.
Think about how gravitational they are and how much they are not torn apart.
The most important thing is that these dark clusters of galaxies are not small, some are as big as the Milky Way.
Of course, it would be understandable if these dark clusters were new to the Comae cluster.
After all, it takes time to tear a galaxy cluster to pieces, but recent studies have found that these dark galaxies have existed in the Comae cluster for billions of years.
Now we can only make a simple inference about this phenomenon.
Dark matter in the universe accounts for about 85% of all matter, and the source of gravity is mass, and the greater the mass, the greater the gravitational force.
Therefore, scientists deduce that if dark galaxies want to maintain equilibrium without being torn apart by other galaxies, they need enough gravity, and that dark galaxies do not have enough star mass to support this gravitational pull, so only a large amount of dark matter in the center of the dark galaxy will do.
This dark matter accounts for 98% of all matter in dark galaxies.
Of course, this is just speculation.
So far, scientists have found 854 such dark galaxies, of which 332 are about the size of the Milky Way.
Some scientists even judge that there are more dark clusters of galaxies in the universe than there are normal galaxies.