What are some interesting knowledge about the cold universe?

After the world's first astronaut went into space more than half a century ago, mankind entered a brand-new space age. The following is a set of cold knowledge after human exploration of the universe.

One: What interesting knowledge of the universe is there in the selected astronomical science popularization? 1. People can't feel the movement of the earth.

Because the earth is huge relative to people, any reference we see is also on the earth, and we are also moving with the earth, and the earth runs very smoothly, so we don't feel the earth moving at all.

2. Why do clouds move?

Many people have always believed that the reason of cloud movement is the rotation of the earth. In fact, it is the constantly flowing air that causes the flow of clouds. Generally speaking, the faster the air moves, the faster the cloud moves.

The structure of the universe is like the brain.

Scientists have found that the deep space image of the universe is very similar to the neural network of the human brain. In fact, this statement is not very accurate, but the human brain is imitating the structure of the universe, just don't know when the brain discovered the secret of the universe.

4. the magical hydrogen element

Hydrogen occupies more than 90% of the visible matter in the universe. Hydrogen exists not only in gaseous, solid and liquid forms, but also in the fourth form of metallic hydrogen, which is made by scientists under high pressure in the laboratory. This metallic hydrogen can be made into a room temperature superconductor.

5. The reason why stars can shine.

The reason why stars can emit light and heat is that the core temperature is high, and thermonuclear reaction can make stars emit light, while the core temperature of ordinary planets is low, which is far from the temperature where thermonuclear reaction occurs. When the mass of a giant gaseous planet reaches a certain level, it is possible to turn it into a star.

6. You can directly see the number of stars.

Although the number of stars in the Milky Way is about 250 billion to 400 billion, no matter how good the field of vision is, there are only 3,000 stars that can be directly seen in the night sky, and there are about 7,000 stars that can be seen on the whole earth. Most of the stars emit light that is invisible to the naked eye.

7. The color of the sun

Although the sun we see is a star that turns red in the morning and white at noon, it is actually a white and yellow dwarf. The sun turns white at noon because the light scattered by the air to this position of the sun is not obvious.

8. Seasonal changes of the eight planets

Of the eight planets in the solar system, only the Earth and Mars have seasonal changes, and other planets have extreme days and nights because they are too close or too far away. The most wonderful thing is that Venus has no seasonal change, because Venus's rotation angle is very small, and its rotation period is almost the same as that of period of revolution, resulting in no illumination difference.

9. It is easier to jump on the moon than to walk.

We see that NASA astronauts are very heavy when walking on the moon, because the gravity is too small to keep their balance. Walking is more laborious than jumping, and it takes a lot of physical strength to keep your body balanced in all low gravity places.

10, how hot is the sun?

The sun is really a hot yellow dwarf, with a core temperature as high as150,000℃ and a surface temperature as low as 6000℃. However, the temperature of the corona layer can reach 654.38 million℃. It is now believed that the solar magnetic field is the main reason for the high temperature of the corona.

1 1. The sun will not hit other stars.

Although there are hundreds of billions of stars in the Milky Way, the distance between each star is several light years, and all the stars are running in the same direction, so there will be no star collision in theory. Even if the Milky Way and Andromeda merge in the future, it will be difficult to have a star collision, but many stars may be thrown out of the Milky Way.

I just don't know if the sun at the edge of the galaxy will be thrown out when the galaxies merge.

Two: What are the interesting knowledge about the cold universe? When we observe space, we are also looking for our own origins. Our story is the story of the universe, because we are the real children of stars. Every atom and molecule injected into our bodies is the whole history from BIGBANG to the present.

1. The earth is not flat, but the universe is flat.

According to Einstein's general theory of relativity, the universe has three possible shapes: open, closed and flat.

The measurement of cosmic microwave background (CMBR) by Wilkinson microwave anisotropy detector reveals that the universe is flat.

2. The age of the universe is 65.438+0.38 billion.

An earlier way to confirm this value is to measure the abundance of some radioactive nuclei, and the observation of globular clusters of the oldest stars is also close to this value.

The center of the universe does not exist.

The earth is not the center of the universe, nor is our galaxy. The universe has no center, and every galaxy is expanding with each other.

4. The universe is quiet.

There is no atmosphere in space, that is to say, there is no medium and way for sound to spread and it cannot be heard. Astronauts keep in touch in space by radio, because radio waves can still be sent and received.

The universe is full of invisible things.

Most of the universe is made up of invisible things. In fact, according to astronomers, the stars, planets and galaxies that can be detected only account for 4% of the universe. The other 96% is made up of invisible or incomprehensible substances.

These elusive substances, called dark energy and dark matter, have not been detected, but astronomers have established their existence on the influence of gravity on normal matter.

6. There is floating water in the universe.

Astronomers found a huge water vapor cloud somewhere about 1000 billion light years away, and its mass is 140 trillion times that of water in the earth's oceans. This is the largest water gathering place discovered so far.

No one knows how many stars there are in the universe.

It is impossible to predict how many stars there are in our universe. Now, according to the estimation of scientists and astronomers, there may be 200 billion to 400 billion stars in the Milky Way.

8. The earliest recorder of Halley's Comet came from China.

In the autumn of 6 13 BC (the 14th year of Lu Wengong's Spring and Autumn Period), a star entered the Beidou. (In the autumn of 6 13 BC, this comet came out of nowhere and brought its bad luck to the Beidou constellation. This is the first exact record of Halley's comet in the world.

9. The largest asteroid in the solar system is a huge space rock named Ceres.

This asteroid is sometimes called a dwarf planet with a diameter of 600 miles. It is by far the largest asteroid belt between Mars and Jupiter, accounting for one third of its mass. Ceres has a surface area about the same as the land area of India or Argentina.

The unmanned Dawn spacecraft has completed its mission around Ceres.

ceres

10. Polaris does not refer to a single star, but is constantly changing.

For example, two or three thousand years ago, the ancients said that the Polaris we saw was different from the Polaris we see today. In 3000 BC, people thought that the Polaris was Thuban, the alpha dragon god. In about 13000 years, Vega will become the new North Star. So now Polaris is actually a multi-star system.

This is because the direction of the earth's axis is changing.

Astronomers have found that it takes about 25,800 years for the earth's axis to precess once, which means that the direction of the earth's axis will pass through a circle in this period of 25,800 years. This circle will of course pass through different stars, so it is impossible to say that Polaris is a certain star. As shown in the figure below, the earth's axis usually points to these stars.

1 1. 99% of the mass of our solar system is the sun.

The sun is very dense, accounting for 99% of the mass of our entire solar system. That's why it can dominate all the planets by gravity.

Technically speaking, our sun is a "G-type main sequence star", which means that about 600 million tons of hydrogen is fused into helium every second. As a by-product, it also converts about 4 million tons of substances into energy.

When the sun dies, it will become a red giant, devouring the earth and everything on it. But don't worry, it won't happen in 5 billion years.

12. The footprints on the moon will exist until the next 1 100 million years.

Because the moon has no atmosphere, no wind erodes the surface, and no water washes the footprints. Therefore, the footprints of Apollo astronauts, as well as space prints and roaming car prints, will stay there for millions of years.

13. The moon is gradually moving away from the earth.

Every year, the moon drifts 3.8 centimeters from the earth. Scientists do believe that eventually, the moon will be out of the range of gravity of the earth.

14. A day on Venus is longer than a year!

The rotation period of the earth is 24 hours. We define 24 hours as 1 Earth Day. Then Earth period of revolution is 365 Earth Days.

earth rotation

So on the earth, a day is 24 hours, that is, 1 Earth Day, and a year is 365 Earth Days.

Earth revolution

Let's compare Venus through the earth.

The rotation period of Venus is 243 Earth Days. Period of revolution of Venus is 225 Earth Days. So on Venus, there are 243 Earth Days in a day and 225 Earth Days in a year. It's like a year!

In addition, the sun rises once every 1 17 earth days, which means that the sun only rises twice a year, strictly speaking, on the same day. Since Venus also rotates clockwise, the sun will rise in the west and set in the east.

15. The black hole photographed for the first time in history is 3 million times that of the earth.

The first black hole photo released in April 20 19 shows a halo composed of dust and gas.

It is said that it is 365,438+0 trillion miles away from the earth. This photo was taken by the Horizon Telescope (EHT). With the help of eight radio telescopes distributed all over the world, the telescopes jointly observed the same target source and recorded data, forming a virtual telescope with an aperture equivalent to the diameter of the earth, which improved the angular resolution of the telescope to the level of observing the event horizon scale structure.

Black holes and gravitational waves

16. If two metals of the same type touch in the universe, they will stick together permanently.

This magical effect is called cold welding. This happens because the atoms of a single metal sheet can't recognize that they are different metal sheets, so these metal sheets will be combined.

This will not happen on earth, because there is air and water to separate these metal blocks. This effect has a great influence on the future spacecraft construction and the metal structure in vacuum.

17. The human body can only survive in space 15 seconds.

Without the protection of spacesuit, the human body can only survive in space for about 15 seconds, which is the time that oxygen can be maintained in the body. In this short time, it will experience blood boiling, body swelling and unconsciousness.

So it is not difficult to understand that the cost of NASA spacesuit is about 12000000 dollars. However, 70% of the total cost is used for backpacks and control modules.

18. Maybe our world is virtual.

Musk, a big shot in science and technology, said: "The probability that we live in the real world is only one in a billion." A Nobel Prize winner once said: "At present, human beings have not discovered alien creatures, mainly because their civilization level is much higher than ours. Humans are controlled by their technical programs, just like humans are manipulating AI technology. " All kinds of interpersonal activities in real society may be arranged by aliens in advance. As for their ultimate goal, we have no way of knowing.

19. The most likely outcome of the universe is the Great Freeze.

Observations of the farthest galaxies show that the universe is expanding at an accelerated rate. This, together with data showing that the universe is cooling, leads us to believe that the most likely outcome of our universe is a big freeze.

In other words, eventually there will be no available heat (energy) in the universe. The great freeze is also known as the heat silence.

1996, carl sagan, an astrophysicist and famous popular science writer, said a very famous sentence: "At this little point, everyone you love, everyone you know, everyone you have heard of, and everyone who once existed, spent their lives there. Here are all joys and sufferings, thousands of confident religious, ideological and economic theories, every hunter and explorer, every hero and coward, every creator and destroyer of civilization, every king and farmer, every young couple in love, every hopeful child, every parent, inventor and explorer, every moral teacher, every corrupt politician, every superstar.