What is a meteor shower?

Groups of meteors formed a meteor shower. A meteor shower looks like a falling meteor in the night sky. This point or this small sky area is called the radiation point of meteor shower. Meteor shower is usually named after the constellation in the sky where the radiant point of meteor shower is located to distinguish meteor showers in different directions. For example, every year165438+1October 1 7 or so, the radiant point of the meteor shower is in Leo, so it is named Leonid meteor shower. Orion meteor shower, Aquarius meteor shower and Perseid meteor shower are also named in this way. A single meteor is random in direction and time, and there is no radiation point at all. This kind of meteor is called accidental meteor. The importance of meteor shower is essentially different from accidental meteor shower.

One of the characteristics is that the opposite extension lines of all meteors intersect at the radiation point.

Meteor showers in the solar system include comets, asteroids and some smaller celestial bodies in addition to the eight planets, dwarf planets and their satellites. Although small in size, small celestial bodies revolve around the sun like the eight planets and dwarf planets. If they have a chance to pass near the earth, they may break into the earth's atmosphere at a speed of tens of kilometers per second. Due to the intense friction with the earth's atmosphere, huge kinetic energy is converted into heat energy, which ionizes the matter and gives off dazzling light. This is the meteor that we often see.

Meteor shower is a group of meteors, which looks like a special celestial phenomenon that appears and falls in the night sky. This point or a small sky area is called the radiation point of meteor shower. In order to distinguish meteor showers in different directions, meteor showers are usually named after the constellations in the sky where the radiant points of meteor showers are located. For example, every year165438+1October 17 or so, the radiant point of the meteor shower is in Leo, so it is named Leonid meteor shower. Other popular meteor showers include Aquarius meteor shower, Orion meteor shower and Perseid meteor shower.

Some meteors are single, the direction and time are random, and there are no radiation points at all. This kind of meteor is called accidental meteor. Meteor showers are essentially different from occasional meteors. An important feature of meteor shower is that the reverse extension lines of all meteors intersect at the radiation point.

The scale of meteor showers varies greatly. Sometimes only a few meteors appear in an hour, but they all seem to "flow out" from the same radiation point, so they also belong to the category of meteor showers; Sometimes in a very short time, thousands of meteors can be seen at the same radiation point, just like fireworks in festivals. When the number of meteors per hour exceeds 1000, it is called "star rain".

Occasional meteors are produced every day, and the time and area of occurrence are random. Meteor showers are periodic in time, and some of them can be predicted scientifically, so they are also called periodic meteors. In addition, it is an important feature of meteor shower that all backward extension lines intersect at the radiation point.

Discovery and historical record of meteor shower

The discovery and record of meteor shower was also the earliest in China. In the Chronicle of Bamboo Slips, there is a record that in the fifteenth year of Xia Emperor, the stars fell like rain at night. The most detailed record can be found in Zuo Zhuan: "In the summer and April of the seventh year of Duke Zhuang of Lu, the stars disappeared, and the stars rained down at night." The seventh year of Duke Zhuang of Lu was 687 BC, which was the earliest record of Lyra meteor shower in the world.

There were about 180 meteor showers in ancient China. Among them, Lyra meteor shower recorded about 9 times, Perseid meteor shower recorded about 12 times, and Leo meteor shower recorded 7 times. These records will also be important information for studying the orbital evolution of meteor groups.

The appearance of meteor shower is quite touching. China's ancient records are also wonderful. Take the record of Lyra meteor shower as an example: In the Northern and Southern Dynasties, Emperor Liu Song's filial piety "Ming five years ... March, the bright moon covered Xuanyuan. ..... there are tens of millions of meteors, long or short, big or small, facing west until dawn. " (Song Shu Tian Wen Zhi) This was in 46 1 year. Of course, the so-called "tens of millions" here is not an exact number, but a general term for "extremely many".

The scene when the Perseid meteor shower appeared, according to ancient records, is also unforgettable. Please see: Tang Xuanzong: "In May of the second year of Kaiyuan, there was a star stream in the northwest, either like an urn or like a bucket, penetrating the North Pole. There are countless small people, and the stars shake to Shunai. " ("The Book of the New Tang Dynasty and the Chronicle of Heaven") In the second year of Kaiyuan, the year was 7 14.

The fact that meteoroids fall to the ground and become meteorites or iron is also recorded in China. There is an explanation in Historical Records that "stars fall to the ground and are also stones". The main component of meteorites discovered in Shen Kuo in the Northern Song Dynasty is iron. He wrote in Volume 20 of Meng Qian's Bi Tan: "In the first year of Zhiping, it was sunny in Changzhou, and the stars were like the moon. See you in the southeast. Occasionally, it will vibrate again and move to the southwest. Another earthquake struck Xu Shiyuan, a citizen of Yixing County. It's far and near, the fire is shining ... it's as deep as a cup. Looking down, the stars are shining in it. It's dark for a long time, but it's still too hot to get close. After a long time, I was surprised that it was more than three feet deep, but I got a round stone. It was still hot, as big as a fist, with a slightly pointed end, as heavy as iron. " The first year of Song Yingzong Zhiping was 1064. Shen Kuo has noticed the composition of meteorites.

In Europe, it was not until after 1803 that people realized that meteorites were the remnants of meteoroids falling to the ground.

The oldest surviving meteorite in China is the Longchuan meteorite in Sichuan, which fell in the Ming Dynasty and was unearthed in the fifty-fifth year of Qing Emperor Kangxi (A.D. 17 16), weighing 58.5 kg. Now it is preserved in Chengdu Institute of Geology.

What is a meteor?

Dust particles in outer space break into the earth's atmosphere and rub against it, generating a lot of heat, thus gasifying the dust particles. In this process, the emitted light forms a meteor. Dust particles are called meteoroids.

speed

A tiny meteoroid is enough to produce light that can be seen hundreds of kilometers away, because of its high speed.

The color of meteors

The color of meteors reflects the chemical composition and reaction temperature of meteoroids: sodium emits orange light, iron is yellow, magnesium is blue-green, calcium is purple and silicon is red.

sound

Meteors usually don't make audible sounds. I didn't see it, so I quietly passed. For very bright meteors, people have heard the sound. These sounds are mainly concentrated in the low frequency band. A very bright meteor, such as a fireball, may hear sounds.

Residual trace

Meteors sometimes leave lasting marks on their tracks. The main color of the residue is mostly green, which is neutral oxygen atoms. The duration is usually 1 to 10 seconds. It can be seen that the afterglow brightness drops rapidly, and generally lasts 1 to 30 minutes when the limiting magnitude is 4 to 5. These bright lights come from hot air and metal atoms in meteoroids.

meteor shower

On some days of the year, a large number of meteors can be seen falling from the same sky area. This is a meteor shower.

Where did the meteor shower come from?

Meteor showers are formed by the rupture of comets.

Why do meteors leave their parent comets?

Comets are mainly composed of ice and dust. When the comet approaches the sun, the ice will evaporate, causing dust particles to eject from the mother body and enter the orbit of the comet like water in a fountain.

Meteor shower activity

Clouds of dust particles in the orbit of comets are called "meteoroids". When meteoroid particles are just ejected from a comet, their distribution is relatively regular. Due to the gravity of the planet, these particles gradually spread all over the orbit of the comet. At present, this process is not very clear. When the earth passes through the meteoroid group, there may be various forms of meteor showers.

An old saying about meteors

1. There is an old saying: "Because a star has fallen, there must be a soul to make up for it. When people die, their souls ascend to heaven, and when you ascend to heaven, you will bring your wishes to God. "

2. The meteor accidentally passed by, and only the dream that stays in my heart all day can capture the scratching moment. Only such a wish can finally come true.

3. A meteor is a star that has fallen into the atmosphere, and it is a "present continuous tense"; The starry sky is just the shadow of the ancient stars, which is a "past tense". Of course, the desire in the present tense needs the help of a meteor.

Seven famous meteor showers

1. Leonid meteor shower

Leonid meteor shower occurs every year from 165438+ 10/4 to 2 1. Generally speaking, the number of meteors is about 10 to 15 per hour, but the Leonid meteor shower has a peak every 33 to 34 years, and the number of meteors can exceed several thousand per hour. This phenomenon is related to the period of Comet templeton Tuttle. When a meteor shower occurs, it seems that the meteor will shoot from a specific point in the sky, which is called the "radiant point", named after the radiant point of the Leonid meteor shower is located in Leo.

2. Gemini meteor shower

Gemini meteor shower appears from June 13 to June 14 every year, and the maximum hourly flow can reach 120, and the maximum flow duration is long. Gemini meteor shower originated from 1983 TB asteroid and was discovered by IRAS satellite in 1983. Scientists judged that this may be the remains of a "burned" comet. Gemini meteor shower radiation point is located in Gemini, which is a famous meteor shower.

3.perseid meteor shower

Perseid meteor shower occurs regularly from July 17 to August 24 every year. It is not only rich, but also almost never misses the starry sky in summer. It is the most suitable meteor shower for non-professional meteor observers, ranking first among the three periodic meteor showers in the whole year. Comet Swift-Tuttle is the mother of Perseid meteor shower. 1992 around the perihelion of the comet, the Perseid meteor shower shone brilliantly, and the number of meteors reached more than 400 per hour.

4. Orion meteor shower

There are two kinds of Orion meteor showers, and the meteor shower whose radiation point is near Betelgeuse usually appears around165438+1October 20th every year. The meteor shower with radiation point near ν occurred from June 65438+1October 15 to June 65438+1October 30, and the maximum day was June 65438+1October 2 1 day. We often say that the Orion meteor shower is the latter, which is caused by the famous Halley's comet. Halley's comet will return to the core of the solar system every 76 years, scattering debris in the orbit of the comet.

5. Taurus meteor shower

The Taurus meteor shower occurs from June 25th 10 to June 25th118+065438. Debris in the orbit of comet Enke formed a meteor shower. On the biggest day, five meteors can be observed flying by every hour. Although the flow is small, it is also because of its stable period.

6. Dragon Meteor

The Draco meteor shower occurs every year from June 6th to June 6th of 10, and the maximum day is June 8th of 10. This meteor shower is one of the three periodic meteor showers in the whole year, with the maximum hourly discharge of 120, and the maximum day is generally close to the new moon, which is less affected by moonlight and provides good observation conditions for observers. Comet Giacobini-Sinner is the origin of the Draco meteor shower.

7.lyra meteor shower

Lyra meteor shower usually appears from April 19 to 23rd every year, and 22nd is usually the maximum day. This meteor shower is the earliest recorded meteor shower in China, and its outbreak in 687 BC is vividly recorded in the ancient book Spring and Autumn Annals. The orbital debris of comet 186 1 I formed the Lyra meteor shower, which, as one of the three periodic meteor showers in the whole year, also occupies an extremely important position in astronomy.

Meteor shower observation in 2007 and its correlation

The second half of the year has arrived. There are many wonderful astronomical phenomena in the second half of the year, and meteor shower is one of them. On August 13, 2007, we are about to usher in the Perseid meteor shower. On September 1 day, will the auriga meteor shower be like a star rain? And the meteor showers of Draco, Leo, Gemini and Ursa minor, as well as the Sagittarius meteor shower early next year. The meteor shower is such a concentrated activity, why not take observation equipment and go out to enjoy the beautiful scenery in the sky?

Here, we must first correct a wrong idea made by some people. Meteor shower is a very advanced astronomical observation, which can't be completed without a telescope. This concept is extremely wrong. Observing meteor showers requires a wide field of vision. If you use a telescope, it will often be greatly reduced, and the number of fashions observed will also be greatly reduced. What's more, the fashion you see can only be seen in the camera, and you can't see anything clearly? So don't wear binoculars when observing meteor showers, which requires our eyes and a clear and dark sky.

Secondly, observing the meteor shower is not as rainy as expected. If you observe some meteor showers with small flow or poor observation conditions (the sky is not dark enough), it is not impossible to see a meteor within a few hours. Of course, the meteor showers I mentioned at the beginning are all famous meteor showers with large flow. As long as there is a clear sky, flow will never let you down.

Meteor shower is an astronomical phenomenon. It means that when comets or asteroids in the solar system, or solid substances and dust particles between planets break into the earth's atmosphere at a speed of 30-60 kilometers per second or more, due to the rapid friction with the atmosphere, huge kinetic energy is converted into huge heat energy and burns. Small ones burn quickly after entering the atmosphere, showing a white light in the night sky, which is fleeting. This is the "meteor". If meteors appear in a certain area of the sky as frequently as raindrops, they are called "meteor showers". Larger, too late to burn into ashes in the atmosphere, it is the "meteorite" that falls to the ground (stony, meteorite; Iron is called a meteorite. Since liberation, meteorite shower has happened five times in China. Studying meteorites is of great significance for human beings to explore the internal structure of the solar system and the earth and explore life on the earth.

Origin and evolution, etc. , has important reference value.

1. may pose a threat to the spacecraft. 1993, the Perseid meteor shower caused the Olympus satellite of the European Space Agency to lose control because it was hit by a meteor.

2. Meteorites may hit people or livestock. There have been no reports that the human body was directly hit by meteorites. 1969, a meteorite broke through the roof of Australia.

3. Ionization effect caused by a large number of meteors breaking into the earth's atmosphere may make long-distance telecommunications abnormal.

4. The radio signal reflected by the long ion column formed by the burning of meteoroids when meteors appear is used for high-frequency or very-high-frequency communication, and the operating distance can reach 1800 km. Meteor communication is of great military significance because it is not affected by solar activity or nuclear explosion.

Interviewee: Lawrence _ 188—— Tong Jinshi, a sixth-grade student.