In the repeated learning day after day, Hua Feng's cultivation did not fall behind. On this day, they learned the naming of asteroids.

In the early days, people liked to use the name of the goddess, and later changed to the acronym of the name of the person, the name of the place, the name of the flower, and even the name of the institution. Some asteroid groups and asteroids are particularly famous, such as the Trojan group, the Apollo group, Icarus, Eros, Hidalgo, etc.

Since asteroids are material from the early solar system, scientists are very interested in their composition. When the space probe passed through the asteroid belt, it was found that the asteroid belt was actually very empty, and the asteroids were very far apart from each other.

Class C-asteroid 253 The name of the asteroid Mathilde consists of two parts: the front part is a permanent number, and the back part is a name. Each confirmed asteroid is given a permanent number, and the discoverer can suggest a name for the asteroid.

The name was not officially adopted until it was approved by the International Astronomical Union, because there are certain conventions for naming asteroids. As a result, some asteroids do not have names, especially those with a permanent number in the tens of thousands. If the asteroid's orbit can be determined with sufficient precision, then its discovery will be confirmed. Before that, it would have had a temporary number, consisting of the year it was discovered and two letters, like 2004 DW.

The first asteroid was discovered by Piazzi in Sicily in 1801, and he named the star Ceres-Ferdinand. The first part is named after Ceres, the patron god of Sicily, and the latter part is named after King Ferdinand IV of Napoli. But international scholars were not satisfied with this, so the second part was removed. Therefore, the official name of the first asteroid was the asteroid 1 Ceres.

Asteroids discovered since then have been named after Roman or Greek gods according to this tradition, such as Homo sapiens, Vesta, Justines, and so on.

But as more and more asteroids were discovered, eventually the names of the classical gods ran out. As a result, later asteroids were named after the discoverer's wife, historical or other important figures, cities, fairy tale characters, or other mythological gods. For example, asteroid 216 is named after Queen Cleopatra of Egypt, asteroid 719 Albert is named after Albert Einstein, asteroid 17744 is named after actress Jodie Foster, asteroid 1773 is named after a dwarf in Grimm's fairy tales, and so on. As at 6 March 2007, a total of 679,373 asteroids with orbits (i.e. provisional designations) had been calculated, 150,106 asteroids with permanent numbers (enquiries) and 12,712 asteroids had been named.

The data obtained by spectroscopic analysis can prove that the surface composition of asteroids is very different.

Asteroids are divided into several categories according to their spectral properties:

C-Asteroid: This type of asteroid accounts for 75% of all asteroids and is therefore the most numerous. The surface of the C-asteroid contains carbon, and the albedo is very low, only about 0.05. It is thought that the C-asteroid is composed of the same as that of a carbonaceous chondrite, a type of stony meteorite. Generally, C-asteroids are mostly distributed in the outer layers of the asteroid belt.

S-asteroids: This type of asteroid accounts for 17% of all asteroids, making it the second most abundant asteroid. S-asteroids are generally found in the inner layers of the asteroid belt. S-asteroids have a relatively high albedo, ranging from 0.15 to 0.25. Their composition is similar to that of ordinary chondrites. Such meteorites are generally composed of silicides.

M-Asteroids: Most of the remaining asteroids fall into this category. These asteroids may have been the metal cores of larger asteroids in the past. Their albedo is similar to that of S-asteroids. Their composition may be similar to that of nickel-iron meteorites.

E-Asteroids: The surface of this type of asteroid is mainly composed of enstatite, and their albedo is relatively high, generally above 0.4. Their composition may be similar to that of enstatite chondrites (another type of stony meteorite).

V-Asteroids: These very rare asteroids have a similar composition to S-asteroids, except that they contain more pyroxene. Astronomers suspect that such asteroids were separated from the upper silicide of Vesta. Vesta has a very large crater on its surface, and it is possible that during its formation the V-asteroid was born.

Occasionally, a very rare stony meteorite, HED-nonchondrites, may be found on Earth with a similar composition to the V-asteroid, and they may also come from Vesta.

G-asteroids: They can be considered a type of C-asteroid. Their spectra are very similar, but in the ultraviolet part of the G-asteroid there are different absorption lines.

B-asteroids: They are similar to C-asteroids and G-asteroids, but have different spectrums of ultraviolet light.

F-asteroid: Also a type of C-asteroid. They differ in the spectrum of the ultraviolet part and lack the absorption line of water.

P-Asteroids: These asteroids have very low albedo and their spectrum is predominantly in the red part. They may be made up of carbon-containing silicides. They are generally found in the extreme outer layers of the asteroid belt.

D-asteroids: These asteroids are similar to P-asteroids in that they have very low albedo and a reddish spectrum.

R-Asteroids: These asteroids are similar to V-asteroids in that their spectrum indicates that they contain more pyroxene and olivine.

A-Asteroids: These asteroids contain a lot of olivine, which are mainly found in the inner layers of the asteroid belt.

T-asteroids: These asteroids are also found in the inner layers of the asteroid belt. Their spectrum is redder and darker, but different from P-asteroids and R-asteroids.

In the past, it was thought that an asteroid was a single single stone, but the density of asteroids is lower than that of stones, and the large craters on their surface indicate that larger asteroids are loosely organized. They are more like huge piles of rubble held together by gravity. In this way, the loose object will not shatter under a large impact, but can absorb the energy of the impact. A single object is shattered by a shock wave under a large impact. In addition, large asteroids rotate slowly. If their rotation speed is high, they may be disintegrated by centrifugal force. Astronomers generally believe that asteroids larger than 200 meters are mainly composed of such piles of rubble. Some of the smaller fragments have become moons for asteroids, such as asteroid 87, which has two moons.

Near-Earth asteroids are asteroids whose orbits intersect the Earth's orbit. In addition to the hundreds of known near-Earth asteroids with a diameter of 4 km, there may be thousands of near-Earth asteroids larger than 1 km in diameter.

Astronomers estimate that these near-Earth asteroids may have been in orbit for 10 million to 100 million years, and their ultimate fate is either to collide with the inner planets (Mercury and Venus orbit the Sun within the Earth's orbit, called inner planets) or to be ejected from the solar system as they approach the planets.

How close are near-Earth asteroids to Earth? In the 30s of the 20 th century, near-Earth asteroids frequently visited Earth. On February 7, 1936, the asteroid Adonis passed by the Earth at a distance of 2.2 million kilometers. On October 30, 1937, the "Hermes" star was even more startled, and it ran 700,000 kilometers to the side of the Earth.

Hundreds of thousands of kilometers may seem out of reach to ordinary people, but they are close to sight in the eyes of astronomers. If these asteroids "encounter" some "misfortune" in their orbit (such as being affected by gravity), they will not be able to hit the Earth.

Astronomers believe that although the orbits of some asteroids do not exactly coincide with the Earth's orbit and have a certain inclination, because the asteroid is perturbated by a large planet, the orbit will intersect with the Earth's orbit, and it is not sensational to collide with the Earth.

In the face of the threat from near-Earth asteroids, countries have taken close monitoring and tracking measures, but there are still asteroids that have slipped through the net. On June 6, 2002, a celestial body with a diameter of about 10 meters hit the Mediterranean Sea. The object detonated and burned in the atmosphere, releasing an energy equivalent to approximately 26,000 tons of ***** (yellow**), which is comparable to the energy released by the explosion of a medium-sized nuclear weapon. At that time, India and Pakistan were on the brink of nuclear war, and if the asteroid hit the region, the consequences would be unimaginable.

Astronomers at the U.S. Near-Earth Asteroid Tracker estimate that there are about 700 NEOs that could hit the Earth and cause disasters. One of the most interesting is a near-Earth asteroid called Apophis, which is about 300 meters in diameter and has the potential to collide with Earth in 2036. According to a report by Cuban state television on the 15th, residents of a small town in central Cuba said that a meteorite fell on the evening of the 14th.

The first close-up of an asteroid was taken in 1971 by Mariner 9 with a photograph of Fourboss and Dymos, both of which were moons of Mars, but were probably captured by Mars. These images show most of the asteroids with irregular, potato-like shapes. Later Voyager programs planned to acquire more images of small moons from gas giants.

The first real close-up of an asteroid was a 951 Gasp that flew by the spacecraft Galileo on its way to Jupiter in 1991

a), then 243 in 1993 Actress and his moon Dactyl.

The first space program dedicated to the exploration of asteroids was Rendezvous-Shoemaker, who photographed 253 Mathilde in 1997 on his way to 433 Eros and successfully landed on Eros in 2001 after completing an orbital orbit.

Among the asteroids that have been briefly visited by spacecraft on voyages to other destinations is the 9969 B. Breel

aille) (Deep Space 1 in 1999) and Anne Frank (A

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k) (Stardust in 2002). In September 2005, the Japanese spacecraft Hayabusa arrived at 25143 to conduct a detailed survey and possibly bring back some samples back to Earth. The Hayabusa's mission encountered some difficulties, including the breaking of two of its three guide wheels, making it difficult for him to maintain the direction of the sun to collect solar energy. The next asteroid exploration program is the European Space Agency's Rosetta (launched in 2004), which is expected to detect 2867 Štei in 2008 and 2010

s and 21 Lutesia.

In 2007, NASA launched the Dawn spacecraft, which will orbit Ceres and Vesta between 2011 and 2015, and may extend its mission to explore Homo sapiens.

Asteroids have been suggested for future Earth resources, as mining sites for rare raw materials, or as building materials for space rest stations.