The gravitational force of the sun on the moon is more than twice that of the earth. Why does the moon keep following the earth?
On the one hand , the gravitational force in the universe causes matter to aggregate to form stars ; The sun makes up 99.86% of the solar system . Therefore, the volume of the sun is equivalent to the entire population of a country with a population of 1 billion. The distance between the moon and the sun is only a thousandth of a light-year, which means that the moon has a strong enough attraction to the sun. So, where does this force come from? If the masses and distances of the sun , the earth and the moon are substituted into the gravitational formula, it can be found that the gravitational force of the sun on the moon is more than twice the gravitational force of the earth on the moon.
The Moon's gravitational pull is aligned with the Earth 's , because there is a region of space around it, and the stars it attracts are dominated by it , not by the larger stars around it . Hill sphere was proposed by American astronomy Hill . In this range , Earth's gravity works, so the Moon orbits the Earth instead of the Sun.
The main factors that affect the size of the Hill sphere are mass ratio and distance . Go further and the Hill sphere is larger . As the moon rises out of space, the distance between it and the Earth becomes smaller, causing the Earth's attraction to the Hill sphere to increase. When the earth leaves the moon, the Hill sphere will also decrease; otherwise, it will increase. If you pull the moon away, or pull the Earth-Moon system closer to the sun, and the moon is outside , it will run away orbit the sun.
Among them, Jupiter has the largest mass, and the Hill sphere has a radius of 53 million km. This is also the reason why Jupiter has the largest number of satellites and can capture nearby comets and asteroids . The Sun's Hill Sphere is about 2 light-years in diameter , and its center , known as the " Oort Cloud ," is made up of many different types of natural sub-satellites . If you look closely, you will find that the relationship between the earth and the moon is not close, they are very close to their respective planets, and there is a certain degree of gravitational interaction between them. Others are farther away from each other. The Earth-Moon system refers to the system orbiting the moon , a typical example of which is a moon about 60,000 kilometers away from the earth , but a moon similar in size to the earth can be seen .
For moons like Io, the Hill sphere is smaller and sits in the planet's larger Hill sphere, making it difficult for it to capture its own target on its own .
The main problem with most moons is the tidal locking of the planets, which, even if they have sub-moons, will lower their orbits and eventually crash into the moon. In the past few years, scientists have conducted a lot of research on these questions. Now they have found that if there is a huge "black hole" between Earth and other planets, they are likely to be sucked in. is this real? Maybe the craters on the far side of the moon look like this.