How terrible is Mercury? The fusion of ice and fire

Mercury is the closest terrestrial planet to the sun, and its average distance from the sun is only 58 million kilometers, which is only about one third of the distance from the earth to the sun. Mercury is relatively small. It is the smallest of the eight planets in the solar system, with a diameter of 4878 kilometers, slightly larger than the moon (the diameter of the moon is 3476 kilometers). In ancient China, Mercury was called a star, because it was close to the sun, and it was difficult to find it in the hot and dazzling light of the sun. Only twice a year, and only in the morning or evening, when you carefully observe the sun, can you see a black spot, that is Mercury. Mercury is very strange. There are several of the eight members of the solar system.

1. Strange name. Mercury is called mercury, but it does not have a drop of water. Mercury is cold and hot. Because it is the closest planet to the sun among the eight planets, the daytime heat on Mercury is unbearable, with the temperature as high as 427℃. Mercury has no atmosphere, and sunlight directly shines on it, which causes the surface temperature of mercury to rise sharply, and the rotation of mercury is very slow, so the daytime on mercury is unbearable, and metals such as zinc and tin will be melted. As for why it is called mercury, this is the name given by Sima Qian in the Western Han Dynasty. The ancients didn't have much astronomical knowledge. The observed mercury was blue-gray, so it was related to the five elements. Gray belongs to water, so it was named Mercury. In fact, Mercury is extremely dry, and it hasn't rained a drop for billions of years. In fact, it doesn't rain at all, and there is no atmosphere, so it will never rain on Mercury.

2. Mercury has the fastest revolution speed and the slowest rotation speed. Mercury is the fastest of the eight brothers! It orbits the sun once every 88 days at a speed of 48 kilometers per second. This is understandable because it is too close to the sun. If it doesn't run fast, it will be caught by the sun and plunged into the sun. Mercury's rotation period is 59 earth days, and its equatorial circumference is15325km. Therefore, the rotation speed of mercury is only a little more than 3 meters per second, which is quite slow, much slower than the rotation speed of the earth of 465 meters per second. Therefore, every day on Mercury is longer than a year. A day on Mercury has 1408 hours, which is equivalent to 176 days on Earth.

The ratio of rotation and revolution of Mercury is 3: 2, and it turns twice every three times. This is a very wonderful proportion and a coupling phenomenon in celestial mechanics. This is an interesting operation mode gradually formed under the strong gravity of the sun and the interaction of many years. Long ago, people thought that the relationship between mercury and the sun was similar to that between the moon and the earth. It was captured by the tidal locking of the sun, which means that it always faces the sun. Later, with the progress of science and the improvement of observation technology, it was found that the rotation of mercury and the sun were not synchronous. Its period of revolution is 88 days and its rotation period is 59 days, so it doesn't always face the sun.

4. Mercury has the largest eccentricity. Mercury has the largest eccentricity among the eight planets in the solar system! It is 0.20563, which means that it is 4600 kilometers away from the sun at the nearest time and 70 million kilometers away from the sun at the farthest time, and the difference between them is as high as 24 million kilometers. Such a large eccentricity is unique in the solar system. The inclination of Mercury's revolution is very small, almost zero, and the measured value is 0.027 degrees, second only to Venus. This means that Mercury revolves vertically around the sun, so there are no seasons on Mercury, which is the same as Venus.

5. The terrible temperature change on Mercury. Because the rotation of Mercury is very slow, and there is no atmospheric protection, the temperature on Mercury during the day is as high as 430, while the temperature on the other side of Mercury facing away from the sun is as low as-170, which means that the temperature difference on Mercury has reached a terrible 600! This is obviously different from other planets in the solar system. No planet has such a big temperature difference. Uranus and Neptune are far away from the sun, and the temperature is very low, but the temperature difference is not big. The temperature on the surface of Venus is very high, up to 460 degrees, which is higher than that of Mercury, but the temperature on Venus is constant and changes little (this is because Venus has a thick atmosphere). Mercury is naked in space, so close to the sun, and the temperature difference is so great.

6. The density of Mercury is the second largest planet in the solar system after the Earth. Mercury, like Venus, Earth and Mars, is one of the four terrestrial planets in the solar system. Like the earth, it has a rock shell with various metal cores inside. The ratio of silicate to metal is 3: 7. The density of mercury is 5.427 g/cm? , second only to the earth's 5.5 15g/cm? . Mercury's core is as high as 60%, while the earth's core only accounts for 17%. Mercury's core is molten hot iron.

7. The surface of Mercury is very similar to the moon, with vast plains and tens of thousands of craters. Mercury was hit by asteroids and comets in turn at the beginning of its formation. Due to the lack of atmospheric protection, Mercury was so exposed that it was hit by others. Its surface is covered with craters of all sizes. The largest crater is the Karoli Basin, with a diameter of 65,438+0,550 kilometers, which can put almost the whole of Australia into it. There are craters, great plains, basins, cliffs and radiation patterns on Mercury. Unlike the way that craters on the moon are named after scientists, craters on Mercury are named after historical figures from various countries. Interestingly, there are 15 craters named after historical figures in China on Mercury. They are Boya, Cai Yan, Li Bai, Bai Juyi, Dong Yuan, Li Qingzhao, Jiang Xie, Liang Kai, Guan Hanqing, Ma Zhiyuan, Zhao Mengfu, Wang Meng, Zhu Da, Cao Xueqin and Lu Xun.

Mercury is bright, but it is too close to the sun to be observed. Mercury is not black. Its visual level is 5.7, which is brighter than the brightest star Sirius. However, because mercury is too close to the sun, its light is very small in the hot sun, so it is difficult to see it with the naked eye. Mercury spends most of its life hidden in the brilliance of the sun and lost in the dazzling sunshine. It can only be seen in the short twilight before sunrise and after sunset, and the time is very short. Astronomer Copernicus lamented that he had never seen Mercury in his life! It is difficult to observe mercury. There are two best observation opportunities this year (202 1), which are 17 at dusk in May and 10/0 at dawn on October 25th.

9. It is easier for humans to detect Mercury than Venus. This is because although mercury is farther away from the earth than Venus, it has no atmosphere, so it is relatively easy to launch a probe to detect mercury, and it is not very difficult for the probe to make a soft landing. So far, the United States and the former Soviet Union have launched many probes to detect mercury, all of which have been successful. This is why we can see a clear picture of Mercury today.

In a word, Mercury is a desolate and silent world. Not only does it have no air (of course, there is no oxygen), but the temperature difference is far from what humans can bear, so there is little hope for humans to land on Mercury. Besides, Mercury, like Venus, is not accompanied by satellites. It flew alone for 4.6 billion years in the elliptical orbit closest to the sun! In contrast, the conditions on Mars outside the Earth are much better. Therefore, in recent years, both the United States and Russia are actively preparing to land on Mars. Generally speaking, in the solar system, only Mars is suitable for earth migration. Other planets, especially Venus and Mercury, are purgatory-like hell on earth, and it is impossible for human beings to stay on it for even a minute, let alone emigrate!