Whenever the sun goes down, night falls. At night, we can only see a little bit of stars. In places where light pollution and atmospheric pollution are serious, even the stars cannot be seen (of course, on rainy days, stars cannot be seen).
Although most of the stars in the night sky are sun-like stars, and many of them are actually larger than the sun and hotter than the sun, for example, the Tianjin IV of the great triangle in summer has a mass of about 19 times that of the sun, a volume of 8 million times that of the sun, and produces energy up to 200,000 times that of the sun per second. But the stars in the night sky are light-years away (2615 light-years away) and too far away from Earth to illuminate Earth's night sky.
Only the closest celestial body to Earth, the Moon, can bring some light to the night. But even during the full moon, the moon's sunlight reflected off The Earth is still very limited, and the moon cannot be used as a source of light for night. Therefore, human beings need to generate artificial light sources through electricity, which will obviously consume a lot of resources.
If a huge artificial light source is placed in the night sky to illuminate the night, which can save a lot of lighting power, this is the "artificial moon" plan.
The artificial moon itself can not emit light, and at present, human beings have not yet mastered controlled nuclear fusion, and the artificial moon can only reflect sunlight like the moon. The artificial moon is actually a large mirror, which can effectively reflect the sun's light and illuminate the ground.
In general, if a human moon is to illuminate the same place, it can only be sent to geosynchronous orbit, nearly 36,000 kilometers from the surface. There, the artificial moon orbits the Earth at a speed equal to the Earth's rotation rate, so it is stationary relative to the surface, so that the sunlight can be reflected to the same place.
However, because geosynchronous orbit is far from the surface, the cost of getting satellites there is high and the efficiency of reflecting sunlight is low. In this regard, the Tianfu Systems Science Research Society in Sichuan, China, has proposed another idea.
According to the plan, three artificial moons will be sent to low Earth orbit one after another, with an orbital altitude of 500 kilometers. At this orbital altitude, the artificial moon orbits the earth every hour and a half, so it is impossible for an artificial moon alone to continuously illuminate the same place.
In order to ensure continuous illumination, three artificial moons will run in the same orbit, with two adjacent moons at an angle of 120°, dividing the orbit into three equal parts. With this deployment, there is always an artificial moon that can shine in the same place. It is estimated that the artificial moon is about 8 times brighter than the full moon, which can illuminate a city at night and save 1.2 billion yuan in electricity bills per year.
According to previous news, the first artificial moon will be launched in 2020. Thereafter, the second and third artificial moons will be launched successively. By 2022, three artificial moons will be deployed and experiments will begin to illuminate the city.
However, some have questioned this. On the other hand, the artificial moon is a serious light pollution. This will not only seriously affect the activity of animals (especially nocturnal animals), but also affect the normal rest of humans. As the earth rotates, day and night alternate, which is itself a law of nature, and the act of breaking the laws of nature may not be a good thing.