Hua Feng found that Yunmeng was also very interested in craters on the lunar surface, and one of the main features of the lunar surface was that some of the "younger" craters often had beautiful "radial stripes", which were bright bands that extended in all directions with craters as radiant points, and it passed through the mountain system, the moon sea and the crater in an almost straight direction. The radial streaks vary in length and intensity, but the most striking is the radiant streak of Tycho Crater, the longest of which is 1,800 kilometers long and is especially spectacular during the full moon. Secondly, the two craters of Copernicus and Kepler also have quite beautiful radial lines. According to statistics, there are 50 craters with radial lines.

The cause of the formation of radiation streaks has not yet been determined. In essence, it is closely related to the theory of the formation of craters. Many people are inclined to the theory of small object impacts, believing that on the moon, where there is no atmosphere and little gravity, small object impacts can send hot fragments flying very far. Other scientists believe that the role of volcanoes cannot be ruled out, and that eruptions during volcanic eruptions may also form radiation shapes that scatter in all directions.

There are many famous rift valleys on Earth, such as the Great Rift Valley. There are also such structures on the lunar surface---- and those large black cracks that appear to be curvy are the moon valleys, some of which stretch for hundreds to thousands of kilometers, and the width varies from thousands to tens of kilometers. Most of the wider Moon Valleys are found in the flatter areas of the Moon Land, while the narrower, smaller Moon Valleys (sometimes referred to as Moon Creeks) are found everywhere.

The most famous Moon Valley is the Great Moon Valley of the Alps, which connects the Rainy Sea and the Cold Sea to the southeast of Plato's Crater, which cuts off the Alps on the Moon, which is very spectacular. Photographs taken from space estimate that it is 130 kilometers long and 10-12 kilometers wide.

On October 5, 2014, scientists discovered a giant square structure hidden underground on the moon. The structure is 2,500 kilometers wide and scientists believe it is an ancient rift system that was later filled with magma.

The surface of the Moon is covered by huge layers of basalt (volcanic lava). Early astronomers believed that the dark areas of the moon's surface were vast oceans, and for this reason, they called them "ma."

e", which means "sea" in Latin, is of course false, these dark areas are actually plains made of basalt. In addition to the basalt formations, the dark areas of the moon are also present with other volcanic features. The most prominent, such as the sinuous lunar glyphs, black sediments, volcanic garden tops, and volcanic cones. However, none of these features are significant, and they are only a small fraction of the volcanic traces on the surface of the moon.

Compared to the earth's volcanoes, lunar volcanoes can be described as old. Most lunar volcanoes are between 3 and 4 billion years old, typical of the plains of the dark zone, 3.5 billion years old, and the youngest lunar volcanoes are 100 million years old. In geological time, the earth's volcanoes belong to the youth period, and the age is generally less than 100,000 years.

The oldest rock formations on Earth are only 3.9 billion years old, and the oldest submarine basalt is only 2 million years old. While the young Earth's volcanoes are still very active, the Moon shows no recent signs of volcanic and geological activity, which is why astronomers call the Moon a "extinguished" planet.

The earth's volcanoes are mostly distributed in chains. In the Andes, for example, volcanic chains outline the edge of a lithospheric plate. The chain of mountains on the island of Hawaii shows hot zones of plate activity. There are no signs of plate tectonics on the Moon. Typical lunar volcanoes are mostly at the bottom of huge ancient impact craters. As a result, most of the dark areas of the Moon have a circular appearance. The edges of impact basins tend to be surrounded by mountains, surrounding shady areas.

The dark zone of the Moon is mainly on the front side of the Moon. Covers almost 1/3 of the area on this side. On the far side of the Moon, the dark zone occupies only 2% of the area. However, the terrain on the far side of the moon is relatively higher and the lunar crust is thicker. It can be seen that the main factors controlling lunar volcanism are the height of the terrain and the thickness of the lunar crust.

In 1760 it was speculated that the distance of the planets in the solar system from the sun constituted a simple series of numbers. According to this series, there is a gap between Mars and Jupiter, and there should also be a planet between the two planets. At the end of the 18th century, many people began to search for this undiscovered planet.

The famous Titius-Bode rule is one such example. At that time, European astronomers organized the world's first international scientific research project, and under the leadership of the Gotha Observatory, the day was divided into 24 zones, in which European astronomers systematically searched for the planet known as the "ghost". But nothing came of the project.

The discovery of the asteroid was closely linked to the Titius-Bode rule, according to which there should be a planet at a distance of 2.8 AU from the Sun, where Piacci, the first asteroid, Ceres, was discovered on New Year's Day 1801.

On the night of January 1, 1801, Giusep Piazzi discovered a star in the constellation Taurus at the observatory in Palermo, Sicily, which could not be found on the star chart. At first he didn't think it would be another comet. But when its orbit was determined, it turned out that it was not a comet, but more like a small planet. Piazzi calls it Ce

Es (Kerres, goddess of cereals and farming, is the beauty of the grain in Sicily), also known as Ceres.

In the following years, Homo sapiens, Marriage and Vesta, which are close to Ceres, were discovered. The introduction of astrophotography and the use of flash comparators have led to a significant increase in the annual rate of asteroid discovery. Piazzi himself did not participate in the project to find the "ghost", but when he heard about it, he suspected that he had found the "ghost", so he continued to observe the star for several days afterward. He reported his findings to the Gotha Observatory, but at first he claimed that he had found a comet. Piazzi became ill after this and was unable to continue his observations. His discovery report took a long time to reach Gotha, by which time the star had moved in the direction of the Sun and could no longer be found.

By the 19th century, several hundred had been discovered, and the number was still growing at a rate of several hundred per year. There is no doubt that there must be hundreds of asteroids that are too small to be observed on Earth. As of 2018, 26 asteroids are known to be larger than 200 kilometers in diameter.

Observations of these visible asteroids are almost complete, and as far as we know, about 99% of the asteroids are less than 100 kilometers in diameter. The cataloguing of asteroids with diameters between 10 and 100 kilometers is halfway complete. But we know that there are even smaller asteroids, perhaps nearly a million asteroids with a diameter of about 1 kilometer. The sum of the masses of all asteroids is smaller than the mass of the Moon.

At this time, Gauss invented a method of calculating the orbits of planets and comets, using which only a few position points were needed to calculate the orbit of a celestial body. After reading Piazzi's discovery, Gauss calculated the position of the celestial object and sent it to Gotha. Olbers rediscovered the star on the night of December 31, 1801. Later it received the name Ceres. In 1802 Olbers discovered another celestial object, which he named Homo sapiens. In 1803 the planet Marriage was discovered, and in 1807 Vesta was discovered. It wasn't until 1845 that the fifth asteroid, Innova, was discovered, but many asteroids were discovered soon after. By 1890 there were about 300 known asteroids.

In 1890, photography entered astronomy, giving a great impetus to the development of astronomy. Previously, to discover an asteroid, astronomers had to record the position of each suspicious star for a long time, comparing the changes between them and the positions of the surrounding stars. But on a photographic negative, an asteroid moving relative to a star can easily be determined by pulling a line on the negative. And as the negatives become more sensitive, they quickly become more sensitive than the human eye, allowing even fainter asteroids to be spotted. The introduction of photography led to a huge increase in the number of asteroids discovered.

In 1990, the technology of photographing the electric element of the electric element was introduced, and the improvement of the technology of computer analysis electron photography made it possible to discover more asteroids in a short period of time. The number of known asteroids is about 220,000.

Once an asteroid's orbit is determined, astronomers can estimate its size based on an analysis of its brightness and albedo. To analyze the albedo of an asteroid, astronomers generally use both visible and infrared measurements. However, this method is still unreliable, because the surface structure and composition of each asteroid may be different, so the analysis of albedo is often more wrong.

More accurate data can be obtained using radar observations. Astronomers use radio telescopes as high-power generators to project intense radio waves onto asteroids. The distance of the asteroid can be calculated by measuring the velocity at which the reflected waves arrive. Analysis of other data (diffraction data) can deduce the shape and size of the asteroid. In addition, observing asteroid occultations can also be used to estimate the size of the asteroid more accurately.

By 1940, there were already 1,564 asteroids with permanent numbers. Among them, the German astronomers Enke and Hansen are particularly useful for their expertise in orbital calculations, and Wolf and Reinmut have made many observational discoveries.

Before the age of space travel, asteroids were only pinpoint-sized points of light even under the largest telescopes, so their shape and topography remained unknown mysteries.

Before 1991, asteroid data was obtained through ground-based observations.

In 1991, the spaceship Galileo Galilei flew by the 951 Gasp

a), the first real close-up of an asteroid was filmed in 1993, when Galileo Galilei flew past 243 Galore and his moon Dactyl.

In 1997, the first space program dedicated to the exploration of asteroids was Rendezvous-Shoemaker.

On June 27, 1997, the NEAR probe passed by the asteroid 253 Mathilde. This rare opportunity allowed scientists to get a closer look at the carbon-rich C-type asteroid for the first time. Since the NEAR probe was not specifically examined for it, the visit became a visit to it. NEAR was used in January 1999 for E

OS asteroids are investigated.

In total, about 700,000 asteroids have been discovered in the solar system, but this is probably only a small fraction of all asteroids, with only a few of these asteroids larger than 100 kilometers in diameter.