What does the moon mean to mankind?

Looking up, I found it was moonlight, and it sank again. I suddenly remembered home? The moon seems out of reach for the ancients, and it seems to have no other function except to emit faint light at night; But with the development of science, scientists discovered the existence of the moon, which is of special significance to mankind.

Forming ocean tides

The moon is 3476 kilometers in diameter and its mass is 8 1 of that of the earth. The most direct impact on the earth is tidal action. 7 1% of the earth's surface area is covered by the ocean, and the periodic movement of sea level is called tide. It was not until Newton established gravity in the seventeenth century that scientists solved the mystery of tides, which were caused by the gravity of the moon and the sun, among which the gravity of the moon had the greatest influence.

The existence of tides accelerates the flow of energy (especially absorbed solar radiation) in the earth's oceans, makes the exchange of materials in marine ecosystems more frequent, and is conducive to the growth of marine ecosystems.

Slow down the rotation of the earth.

Because of the tidal action of the moon on the earth, there is relative motion between the ocean uplift and the earth, which produces internal friction and consumes the rotational kinetic energy of the earth, and the direct influence is to reduce the rotational speed of the earth.

At present, the earth's rotation period increases by 1 second every 65438+ million years. A billion years ago, one day on earth was 17 hour, and now it is 23 hours and 56 minutes. In the future, the rotation speed of the earth will be slower and slower until it is tidal locking by the sun, and the solar system may be destroyed before that day.

Stable earth axis

There is precession in the process of the earth's rotation, that is to say, the earth's axis itself is not stable, and it will change periodically, which will change the position of the Tropic of Cancer periodically. It's 380,000 kilometers to distance to the moon, and the existence of the moon makes the angular momentum of the Earth-Moon system bigger, which has a direct impact on weakening the precession of the earth and making the earth axis more stable.

The physical principle can be illustrated by a simple example: when turning in place, it is easy to lose balance when holding your chest with your hands, but it is more stable when turning in place with your hands spread out, and it is not easy to fall.

The stability of the earth's axis is conducive to the stability of the climate, which is an important guarantee for the evolution of life on earth. Otherwise, a major climate change will occur every few thousand years, which will be a devastating disaster for animals and plants.

Calendar making

The calendar based on the revolution of the earth is called the solar calendar, the calendar based on the revolution of the moon is called the lunar calendar, and the calendar based on the combination of the two laws is called the yin-yang calendar. The lunar calendar we use belongs to the lunar calendar, which has the advantages of both lunar and solar calendars.

It takes 27.32 days for the moon to go around the earth once. Because of the revolution of the earth itself, the moon phase changes later, and the cycle of the moon phase changes is 29.53 days, so the lunar calendar has 29 days and 30 days in a month, which is based on the moon phase changes. The change of moon phase affects astronomical observation and tidal change.

Space springboard

Man's exploration of space is cyclical and gradual. The nearest planet to the earth is Venus, with a harsh surface environment, an average temperature of 450℃ and perennial acid rain. Although Mars is a planet suitable for human migration, it is too far away for human beings at this stage, and the exploration cost is very high.

The gravity of the moon is only one-sixth of that of the earth, which is very conducive to the landing and take-off of spacecraft. Therefore, the first step of human migration must be to use the moon as the first space springboard.

Helium -3 resource

Controlled nuclear fusion is the ultimate energy of mankind, and helium -3, as a clean nuclear fusion material, is the energy material that mankind dreams of; On earth, the world's helium -3 resources add up to only half a ton, which makes helium -3 very expensive.

On the moon, because the moon has no atmosphere and magnetic field, the solar wind directly reaches the surface of the moon. After billions of years of solar wind blowing, it is conservatively estimated that the accumulated helium -3 on the surface of the moon exceeds 6,543,800 tons, so the helium -3 on the moon will definitely become an important energy source for mankind in the future.