In the early days of the universe, the movement of gravity drove the movement of the original gas cloud. Due to the friction between the moving gas clouds, they start to rotate. With the gathering of a large amount of gases, stars have begun to form, and then the original galaxy is formed.

Then, the gravity caused the collision and coexistence of these original galaxies, and finally formed the galaxy we saw today.

This process has experienced tens of billions of years. In different environments, the forms of galaxies are different. Just like the clouds in the sky, due to the changes in the air pressure and temperature of the earth, they will form a different look in different areas.

Humans are the only wisdom on the earth. Since the primitive era, humans have made infinite longing for the vast starry sky. It's just that in the hearts of ancient humans, there is more fear of the starry sky. Especially when they saw the meteorites in the sky falling to the ground, they were even more afraid.

With the continuous development of human beings, we have entered the age of science and technology from primitive times. Although human beings have only entered the age of science and technology for a short period of more than 200 years, the achievements we have made are amazing. With the help of technology, we are also off Earth.

In the early days of exploring the universe, our observation technology is relatively low, and the scope of seeing is very limited. At that time, scientists believed that the galaxy was the entire universe, and the number of stars in the galaxy was not large.

But in fact, the galaxy is a huge star system, with more than 200 billion stars. The sun is an ordinary member of the galaxy. All the stars we see are almost members of the Milky Way.

Due to the influence of the earth's atmosphere and interstellar material, and the restrictions of human vision, we can see more than 6,000 stars throughout the year, which only accounts for a small part of the galaxy star.

The lifetime of a star depends on its capacity and energy consumption rate. Massive stars have fast production and energy, so their lives are short; Low-mass stars have slow production and energy consumption and live a long time. Our sun is 10 billion years old from birth to death.

A giant star 20 times more massive than the sun can be created very quickly. It only takes 10 million years from birth to death. Its lifespan is one thousandth that of the sun.

With the proposal of the Big Bang theory, scientists have discovered that the universe is 13.8 billion years old. The scope of human observation of the universe has reached 93 billion light years. The calculation of this range is actually based on the theory of the Big Bang and the speed of photons.

With the continuous improvement of our observation ability, we have become more and more understanding of the universe, and we feel that we humans are small. Although our observation scope is very broad, there is still a long way to go before we go to the field detection. After all, we have not even gone out of a small solar system.