Copernicus’ heliocentric theory reduced the earth, which was originally the center of the universe, to an ordinary planet, which was of extremely great significance in the history of scientific development. After careful calculations, scientists at that time measured the distances from Mercury, Venus, Earth, Mars, Jupiter and Saturn to the sun. When the astronomer Tydeus arranged the distances of these planets from the sun into a table, he soon discovered that the distances from the planets to the sun were not just as large as they wanted, but were determined by a kind of mathematics. rules. This teaching rule is now known as the Titius-Bode rule. This rule can be simply described as follows:
First write two numbers 0?0 and 0?3, and then write the following numbers, each of which is twice as large as the previous one, so that you get a column The numbers are 0?0, 0?3, 0?6, 1?2, 2?4, 4?8, 9?6. Then add 0.4 to each number in this column, and you will get a new series of numbers: 0.4, 0.7, 1.0, 1.6, 2.8, 5.2, 10. If you compare this series of numbers with the distances of each planet from the sun, you will see a strange distribution - except for the number 2?8, several other numbers correspond to the distance of a certain planet from the sun ( Please see the table below). How close the actual numbers are to the rule! After Herschel discovered Uranus in 1781, people immediately used its distance to verify the Tidius-Bode rule. The rule number is: 9?6×2+4=19?6, and the real distance was confirmed to be 19?18, which is basically consistent again, so many astronomers came to the conclusion: Titius-Bode's rule Not a random coincidence.
Planet name Tidius-Bode distribution number Distance from the sun Mercury 0?40?39 Venus 0?70?72 Earth 1?01?0 Mars 1?61?52?2?8 Jupiter The position of the numbers 2-8 in the 5?25?2 Saturn 10?09?52 rule is empty. Does this "empty seat" have an owner? Who is this owner? It has aroused widespread interest among astronomers. Many people search relentlessly for it. At an international astronomical conference in 1796, French astronomers proposed a plan for collective cooperation to find this planet. Six astronomers formed a team and decided to conduct a systematic search. They predicted that if there was a planet in this area, it must be very small, otherwise it would have been seen by the naked eye. But if it does exist, you can definitely find it with a telescope. So the "celestial police" armed with telescopes began to track and search. But not long after they started working, the planet was discovered by others first. On the night of January 1, 1801, Piazzi, director of the Palermo Observatory on the Italian island of Sicily, discovered a small moving star while mapping a star map of a certain sky area. This was a new planet! On this day, the first day of the 19th century, astronomers are so surprised and excited by the unique New Year gift that science has given to mankind!
Piazzi, the patron goddess of Sicily and Roman mythology The newly discovered asteroid was named after Ceres, the goddess of fertility in Greek mythology. She is Demeter, the god of agriculture in Greek mythology.
Piazzi wrote to the Milan Observatory and the Berlin Observatory, reporting the discovery of a new planet, Ceres. but. Since it was during the Napoleonic Wars, the letter was suppressed for more than two months. It is interesting to say that during this period, the famous German idealist philosopher Hegel published a paper, arbitrarily saying that there could only be 7 planets near the sun, and there could not be 8 in any case. He also ridiculed astronomers for their delusions of searching for unknown planets based only on a table of numbers, which is very ridiculous. However, the irony is that Hegel never imagined that when he wrote this paper, the eighth planet had already been found.
Piazzi fell ill at the end of January. At this time, his letter was still traveling on the road, and Ceres disappeared. The new member that was finally found was lost again. The astronomers were very anxious and tried their best to search. After nearly a year of hard work, they finally found it again on the last night of 1801. It turned out that during this entire year , it has migrated from Taurus to Virgo. This asteroid is located at 2.77 degrees from Titius, which is very close to the number 2.8 in the rule.
In March 1802, when people were observing Ceres, they suddenly discovered another small bright spot near Ceres, which was a new asteroid.
The first discovered Ceres was too small and could not be compared with the large planets, which made scientists very dissatisfied; and the discovery of this second asteroid surprised and embarrassed them. Looking for one planet, but found two. Although it is difficult to understand, it does exist. According to mythological custom, the asteroid was named Athena. She is an important goddess on Mount Olympus, but for some reason she was not given a place among the big planets, but placed on a small planet. Legend has it that Athena is a beautiful, brave, and intelligent goddess who is known as the goddess of wisdom and the goddess of war. Our country has translated this asteroid as Pallas. The image of Athena is very tall, wearing a robe that hangs down to her feet, a war helmet on her head, and a breastplate with the head of the demon Medusa hanging on her chest. She holds a shield in her left hand and has a spear standing in front of her arm. , heroic and heroic. Legend has it that she was born to the god Zeus and the goddess of wisdom Metis. At that time, Zeus was afraid that Metis would give birth to a child more powerful than him and overthrow his rule in the future. Therefore, when Metis became pregnant, he killed her. Swallowed it in one gulp. Later, Zeus felt pain in his head, so he asked Hephaestus, the god of fire, to split his head open with a copper axe. At this time, Athena, who was fully clothed, jumped out of Zeus's head, shouting loudly. Among the gods, Zeus is the most powerful and Metis is the smartest. Therefore, the advantages of these two gods are reflected in Athena, making her the embodiment of power and wisdom. She used her wisdom to teach the Greeks various skills such as spinning, weaving, car building, shipbuilding, metallurgy, iron casting, shoemaking and sculpture. She also invented the plow and rake, and tamed cattle and sheep, so she was the patron saint of agriculture and gardening. She brought the olive tree, a symbol of peace, to the Athenians, and for this reason she became the patron saint of the city of Athens. She was also the patron saint of law and order. Athena helped many Greek heroes and did many useful things for them. She was highly respected and admired by the Greek people.
Two asteroids were found, can more asteroids be found? Scientists began to search again, and soon after they found the asteroids now known as Juno and Vesta. . Juno is the queen of heaven. In Greek mythology, she is called Hera. She is the wife of Zeus. She is also a goddess who speaks her word on the sacred mountain of Olympus. She is the goddess of proof and protection of marriage, so the asteroid named after her is translated as Juno. This queen was jealous by nature, which led to many famous stories, some of which are related to her.
The goddess Vesta, called Hestia in Greek mythology, is the God of Vesta. The asteroid named after her is translated as Vesta. She is also the household god, in charge of the household affairs of all people. She is the sister of Zeus, and there are not many stories about her.
After astronomers found the four asteroids Ceres, Pallas, Juno and Vesta, there was a long hiatus. By 1845, a fifth asteroid, Justice, was discovered. God star. Then a series of new discoveries were made, and the number of asteroids increased rapidly. At first astronomers gave them names after goddesses. But there were more and more asteroids, and although there were many goddesses in Greek and Roman mythology, eventually the names were not enough. Since 1925, newly discovered asteroids have been given temporary names: two Latin letters are added after the year of discovery, the first indicating the time of discovery, in half-month units, in alphabetical order; the second letter, then Indicates the order in which they were discovered during this time period, also in alphabetical order. After the orbit of a newly discovered asteroid is calculated, and after more than two opposition observations, it is given a permanent number and a proper name. Some asteroids are named after characters in mythology, while others are named by the discoverers, such as place names, Scientist names, etc. Nearly 6,000 asteroids have been discovered and numbered so far. Photographic sky surveys have found that there are 500,000 asteroids with brightness greater than photographic magnitude 21.2.
Our country attaches great importance to the observation of asteroids. The Purple Mountain Observatory of the Chinese Academy of Sciences has been engaged in the observation and research of asteroids for many years and has discovered many asteroids. So far, a total of 41 asteroids have been discovered and officially numbered and named by the Purple Mountain Observatory, and they have been recognized by the International Minor Planet Center.
Director Zhang Yuzhe of the Purple Mountain Observatory of the Chinese Academy of Sciences has devoted himself to the study of asteroids and comets for decades and has made great achievements. In 1928, he discovered asteroid No. 1125 in the United States. In memory of his motherland, he named the asteroid "Zhonghua". After liberation, under his leadership, the Purple Mountain Observatory discovered many asteroids that were not numbered in the ephemeris and three comets named after "Purple Mountain".
In order to commemorate his contribution to astronomy, the "International Asteroid Bulletin" published in August 1978 announced that the newly numbered asteroid No. 2051 was named "Zhang".
Asteroids are truly small, with small diameter, small volume, and small mass. Because of its small size, it is indeed not easy to measure the diameter of an asteroid. In recent years, advanced radiation measurements and polarization measurements have been used to more accurately determine the diameters of about 200 larger asteroids. The largest asteroid is Ceres, which has a diameter of about 1,000 kilometers, less than 1/3 of the diameter of the moon; Pallas and Vesta are both about 590 kilometers; Juno has a diameter of about 250 kilometers; The diameter of asteroids is less than 1 kilometer; most asteroids are only tens of kilometers in diameter, and the total volume of asteroids is estimated to be only one thousandth of the volume of the Earth.
Because asteroids are small in size, their masses are also small. Among the larger asteroids, Ceres weighs (11.7±0.6)×1023 grams; Pallas weighs (2.6±0.8)×1023 grams; Vesta weighs (2.4±0 ?2)×1023 grams. The remaining asteroids have smaller masses. It is estimated that the total mass of the asteroid is only 2.1×1024 grams, which is about 4/10000 of the mass of the Earth.
The shapes of asteroids are relatively diverse. Except for Ceres and Vesta, which may be spherical, most of them are irregular. Some are long-grained, some are like stones, and some are like bricks. For example, Eros No. 433 is a three-axis body with lengths of 36 kilometers, 15 kilometers, and 13 kilometers respectively. Some people describe it as like a sausage.
Asteroids themselves do not emit light. Like large planets, they shine by reflecting sunlight. Their apparent brightness is related to their distance from the sun and the earth, as well as their albedo. Vesta, the brightest among them, has a magnitude of about 6 at its brightest and is the only asteroid barely visible to the naked eye. Several other larger asteroids: Ceres with magnitude 7.4, Pallas with magnitude 8.0, and Juno with magnitude 8.7. They all need to be observed with a telescope. The other asteroids are even fainter. It was discovered using telescope photography.
Although asteroids are basically distributed between the orbits of Mars and Jupiter, the semi-major diameter of their orbits is about 2.17 to 3.64 astronomical units. On average, their distance from the sun is 2.8 astronomical units. Units within this distance make up the asteroid belt. However, there are also a few asteroids with special orbits that exceed this range. There are some asteroids that orbit far away from the sun, beyond the orbit of Saturn, and an asteroid has even been discovered that can travel as far as Uranus. There are also some asteroids that have reached within the orbit of Mars and have reached near the Earth. Some even reach within the orbit of the earth. These asteroids that run close to the earth are called near-Earth asteroids. They can be divided into two categories: one type whose perihelion distance is less than 1 astronomical unit, called Apollo type; the other type whose perihelion distance is greater than 1 astronomical unit, called Apollo type. Moore type. Some of these asteroids are very famous. For example, when the asteroid Apollo approached the earth, its closest distance was only 10,000 kilometers, and sometimes its orbit penetrated within the orbit of Venus. The asteroid called Hermes is the record holder for the closest approach to the Earth known so far. Hermes is the messenger of the gods in Greek mythology. He is like the magical eunuch in Chinese legends. He is a scud. His whereabouts are both fast and secretive. In 1937, it passed by only 800,000 kilometers away from the earth (this distance is about twice the distance between the moon and the earth). People called it the "Earth flyer".
There are also asteroids whose orbital radius is roughly the same as that of Jupiter. They are few in number but relatively famous. This type of asteroid is divided into two groups, with the centers each located 60° before and after Jupiter, forming two almost equilateral triangles with the Sun and Jupiter. They are collectively called the Trojan group asteroids. These asteroids are famous because they proved Lagrangian theory. In 1772, Lagrange theoretically proved the restricted three-body problem: if the three bodies are exactly located at the three vertices of an equilateral triangle in motion, and one of the celestial bodies has a small mass, then they will maintain a relatively stable position. . The motion of the Trojan group asteroids is consistent with that of Jupiter. Their average distance from the sun is about the same, and their orbital periods around the sun are also similar. Therefore, they also maintain relative stability with the equilateral triangle formed by the sun and Jupiter.
For the Sun and Jupiter, there are two points that comply with the Lagrangian three-body restriction, denoted L and L′ respectively, and are called Lagrangian points.
These two Lagrange points, one is 60° in front of Jupiter and the other is 60° behind Jupiter. The name of the first asteroid No. 588 that meets the conditions of Lagrangian point is called Achilles. He is Homer. The name of the most courageous Greek general in the epic "Iliad". The second asteroid No. 617 that meets Lagrangian conditions is named Patroclus. He is Achilles's friend and lieutenant. Later, it was agreed that the asteroids near the Lagrange point before Jupiter should be named after Greek heroes, such as Agamemnon, Odysseus, Nestor, etc.; the asteroids after Jupiter should be named after Lagrange. The asteroids near Langian Point are all named after the Trojan warriors who fought against the Greek army, such as Paris, Aeneas, etc. This group of asteroids is collectively called "Trojan Warriors". Because of this decision, some previously named asteroids fell into the wrong camp. The second discovered asteroid No. 617, the Greek hero Patroclus, was mixed into the Trojan army; for the same reason, a Trojan general was also mixed into the Greek army. Hector.
To date, among the more than 3,000 officially numbered asteroids, there are only more than 20 Trojan asteroids. my country's Purple Mountain Observatory discovered four Trojan group asteroids, two of which happened to belong to the Greek camp and two to the Trojan camp. These four asteroids were named after Greek heroes and Trojan heroes respectively.