# Why is mercury so close to the sun and not engulfed? After listening to the answer of the scientist, I suddenly realized

There are eight planets in the solar system. Neptune is the farthest from the sun, and mercury is the nearest. Many people may think that there should be a lot of water on mercury when they hear its name. Otherwise, why call it mercury? When Xiao Bian first knew mercury when he was a child, he also thought that mercury was a planet full of water.

But later, I learned that Mercury is just a water word in its name. How can there be water on its surface when it is away from the sun. Mercury is the closest planet to the sun among the eight planets. Its orbit is so close to the sun. Why is it that it is not pulled into the sun by the gravity of the sun and swallowed? In fact, the answer to this question is not complicated.

The mass of the sun accounts for 99.84% of the total mass of the solar system. Such a large proportion of the mass of the sun will inevitably produce super strong gravity. Under normal circumstances, other planets will be pulled into the sun by the gravity of the sun, and the sun will be engulfed. But the real situation is that the eight planets are stable around the sun. The reason for this is related to the rotation and revolution of the planets themselves.

When the planet rotates at a high speed, it will also revolve around the sun at a high speed, and the closer it is to the sun, the faster it is. Therefore, Mercury’s speed of revolution is the fastest, reaching 47.4 kilometers per second. When the planet revolves and rotates, it will produce a centripetal force, which can balance the gravity produced by the sun. When the force forms a balance in a certain orbit, the orbit of the planet will also produce.

As long as the mass of the sun does not change significantly, and the mass of the planet does not change significantly, the planet can run stably around the sun. The reason why mercury does not fall into the sun is also the same. Its rotation and revolution are very fast, and the centripetal force is naturally greater. It is necessary to form a balance with the sun’s gravity effectively, and nature will not be swallowed by the sun.

Of course, if you want to survive closer to the earth, mercury naturally has something extraordinary. Otherwise, even if it is not swallowed by the sun, it will be continuously evaporated by the high temperature of the sun. Mercury is an earth like planet, because it is very close to the sun, so it will only appear in the early morning, called Chenxing, or dusk as an evening star. Unless there is an eclipse, mercury is usually invisible in the sun.

After walking out of the earth, we first began to explore several planets close to the earth. Naturally, mercury is also within the scope of scientists’ exploration. So on November 3, 1973, scientists discovered mercury 10, which is the first probe to explore mercury. After arriving at the orbit of mercury, sailor 10 explored mercury successively in March 1974, September 1974 and March 1975, and sent back more than 5000 photos to the ground, providing us with precious information about mercury. From the photos, we can see that Mercury looks like the moon. There are many craters of different sizes, as well as radiation patterns, plains, rifts, basins and other terrain.

It is found that Mercury is the planet with the second highest density in the solar system, second only to the earth, which is in line with the previous guess of scientists. If mercury can move so close to the sun, its density must be very high, and it must also have a very large mass core, which should be an iron core like the earth.

The mass of the earth’s inner core only accounts for 1 / 3 of the total mass of the earth, while the mass of Mercury’s inner core reaches 2 / 3 of the total mass of the planet. It can be seen that during the long years of Mercury’s close orbit around the sun, a lot of material is evaporated by the sun, and most of the material left behind is very dense. Mercury contains more iron than any other known galaxy or planet. Since mercury has an iron core with a very large mass, the probability of its existence of a magnetic field is very high. Through the observation of the detector, mercury does have a magnetic field.

And Mercury also has a thin atmosphere, so it’s not easy for mercury to remain in the atmosphere at such a close distance from the sun. Mercury’s diameter is only 4878 kilometers, and its mass is about 5.58% of the Earth’s. according to its volume, its mass is already very large. The surface of mercury is very similar to the surface of the moon, and it is also covered with dense craters. However, there are not many large craters with a diameter of 20-50 km, while there are many craters with a diameter of more than 100 km.

Mercury’s day and night humidity is also the highest among the planets in the solar system. The temperature at noon can reach above 400 ℃, and the temperature behind the sun drops to – 170 ℃. If we say which planet in the solar system is most similar to the earth, it may belong to mercury. Maybe many people will say, isn’t Mars most similar to the earth? In fact, it’s not. Let’s take a look at these characteristics of the water Star: there is a thin atmosphere, there is an iron core, the core is mainly composed of iron, nickel and other elements, and there is no weak global magnetic field.

The earth has the same characteristics as the other planets. For example, Mars and the earth also have a lot of beliefs, but Mars has no magnetic field, whether there is an iron core similar to the earth is also unknown. On the contrary, mercury has an obvious magnetic field. Although its magnetic field strength is only one percent of that of the earth, for a planet with a diameter of only over 4000 km, the magnetic field strength is already very strong. This is why mercury can be so close to the sun and have a thin atmosphere.

Maybe many people think that Mercury is so close to the sun and the surface humidity is so high that there is unlikely to be water. But the real detection results show that there is a lot of water ice at the poles of mercury. Images taken in 2011 and early 2012 by Mercury’s dual imaging system aboard messenger proved that the bright areas that strongly reflect radar waves are located in the permanent shadow areas of Mercury’s north and south poles.

And in these forever shadowed areas, there is a lot of water ice, because it is not exposed to sunlight and the humidity is very low. These discoveries of mercury have enabled scientists to have more knowledge of mercury. However, people’s knowledge of mercury is still relatively small. Now, no probe has been able to land on mercury, and it is impossible to determine the actual situation of Mercury’s surface. For example, will there be life in the polar water ice?

Any planet with water, whether liquid water or water ice, cannot rule out the possibility of life. The adaptation of life to the environment is far beyond our imagination. Some life may need liquid water to survive, while some life may need extremely cold water ice environment. Everything is possible.

It can be seen that these planets near the earth, mercury, Venus and Mars, all have their own unique features. And now humans have only realized the landing exploration on Mars, so they naturally know a lot about Mars. However, mercury and Venus are really fuzzy observations made by space orbiters, and they can not really land for long-term exploration. This is also the reason why human science and technology are still relatively backward. I believe that with the continuous progress of human science and technology, it will not be too long for the future probe to land on mercury. At that time, we will have a comprehensive understanding of mercury, the planet closest to the sun