PS: A comet (ET) is a celestial body that enters the solar system and moves around the sun with its brightness and shape changes with the solar distance, and the comet material evaporates, forming a hazy comet and a thin stream of material around the ice core. Pen? Interesting? Pavilion wWw. ｂiquge。 info, top, point, novelDue to the pressure of the yang wind, the comet tail always points in the direction of the opposite yang.

1. Comets

A comet (ET) is a celestial body that enters the solar system and moves around the sun with a change in its shape depending on the solar distance, and the comet material evaporates, forming a hazy comet and a thin stream of material around the ice core. Due to the pressure of the yang wind, the tail of the comet always points in the direction that is opposite to the yang.

In 1066, on the eve of the Norman invasion of England, Halley's Comet returned. At that time, people had mixed feelings about this strange celestial body with a long tail in the night sky, believing that it was a kind of warning and foreshadowing of war given by God. Later, when the Normans conquered England, the wife of the Norman commander embroidered the scene of Halley's Comet on a tapestry to commemorate the return of Halley's Comet. Chinese folk derogatorily refer to comets as "broom stars" and "disaster stars". There are many things like this that associate the appearance of comets with human wars, famines, floods, plagues, and other disasters in Chinese and foreign history. A comet is a small, small, cloudy object orbiting the Sun in an oblate orbit (a few in a near-circular orbit).

(1) Comet structure

Comets do not have a fixed volume, and when they are far from the sun, they are very small; As it approaches the sun, the hair becomes larger and larger, the tail becomes longer, and the volume becomes very large. The length of the comet's tail can reach more than 200 million kilometers. The mass of the comet is very small,

The average density of the nucleus of the comet is one gram per cubic centimeter. The material of the comet and tail is thin. Its mass only accounts for 1%~5% of the total mass, or even smaller. Comet material is mainly composed of water, ammonia, methane, cyanide, nitrogen, carbon dioxide, etc., while comet nuclei are composed of a mixture of water, carbon dioxide (dry ice), ammonia, and dust particles that have condensed into ice. It's a "dirty snowball"!

Generally, comets are composed of two parts: the head and tail of the comet.

1. Comet

The comet head includes two parts: the nucleus and the coma. Later, from the 1920 sounding rockets, artificial satellites and spacecraft to explore the comet at close range, it was discovered that the existing comet was surrounded by a layer of giant clouds composed of hydrogen primitives, which was called "comet" or "hydrogen cloud". In this way, we can say that the comet is actually made up of a comet nucleus, a comet, and a comet.

(1) Comet nucleus

The nucleus of the comet is the most central, essential, and dominant part of the comet. Generally considered to be solid, it is composed of stones, iron, dust, ammonia, methane, and ice. The diameter of the comet nucleus is very small, ranging from a few kilometers to a dozen kilometers, and the smallest is only a few meters.

(2) Comet

Comet: It is a planet-like mist of gas and dust around the nucleus of the comet. The radius can reach hundreds of thousands of kilometers, and the average density is less than one billionth of a billion (about 1 gram per cubic centimeter) of the Earth's atmospheric denseness. Found by spectroscopy and radio observations. The main components of the gas in the comet are neutral components and originals, including hydrogen, hydroxyl, oxygen, sulfur, carbon, carbon monoxide, amino, cyanide, sodium, etc., and more complex compounds such as hydrogen cyanide (H) and methyl cyanide (CH3) are also found. These gases flow outward from the center at an average speed of 1-3 km/s.

Comet: A cloud composed of hydrogens outside the coma. It is also known as a hydrogen cloud. The diameter can reach 10,000-10 million kilometers, but some comets do not have comets.

According to the shape and composition characteristics of the comet, it can be divided into "hairless comet", bulb-shaped comet, anchor-shaped comet and so on.

2. Comet tail

Comet's tail begins to appear when the comet approaches the sun about 100 million kilometers (two celestial units), and gradually changes from small to large to long. When the comet passes perihelion (i.e., the comet moves away from the sun) after reaching the closest point to the sun. The tail of the comet gradually becomes smaller. Until there is none. The direction of the comet's tail is generally always extended with the sun on its back, and when the comet approaches the yang, the comet's tail drags behind, and when the comet leaves the yang, the comet's tail becomes the leader. Comet tails are large in size but thin in substance. The length and width of the comet's tail also vary greatly, with the tail generally between 10 million and 150 million kilometers long, and some are surprisingly long. It can cross half the sky, such as the comet that appeared in 1842 with a tail of 120 million kilometers. It can reach from the sun to the orbit of Mars. Generally, the width of the comet tail is between 6,000 and 8,000 kilometers, the widest is 240,000 kilometers, and the narrowest is only 2,000 kilometers.

According to the shape of the comet tail and the magnitude of the positive repulsion, the comet tail is divided into two categories. One type is the "separation tail", which is composed of ionized gases, such as carbon monoxide, hydrogen, carbon dioxide, carbon, hydrogen groups and other ionized components. This type of comet tail is relatively straight, thin and long, so it is also called "gas comet tail" or type 1 comet tail. The other type is the "dust comet tail", which is composed of fine dust, which is yellow in color, and is formed by pushing away the dust under the radiation pressure of sunlight. The comet tail is curved, the curved one is larger, and the wider one is also called the type 2 comet tail; The largest bending program, short and wide, is also known as type 3 comet tail. In addition, there is also a type called "anomalous comet tail", which is a fan-like or long spike-shaped tail that extends in the direction of the yang system. Generally, a comet has more than two different types of tails.

Comets are a very special kind of star that may have an important connection to the origin of life. Comets contain a lot of gases and volatile components. According to the spectral analysis, it is mainly C2, C3, Oh, NH, NH2, CH, Na, C, O and other original groups and original groups. This indicates that comets are rich in organic components. Many scientists have noticed this phenomenon: perhaps, life originated from comets! In 1990, NASA and Daidgrinspoon explained organic dust in strata near the White Age-Chronicle boundary as follows: one or several comets passed over the Earth, leaving behind amino acids that formed this organic dust; It also points out that in the early days of the Earth's formation, comets were able to rain down organic matter on the Earth in this way—the source of life on Earth.

2. Meteors

Meteors and comets are not necessarily related, but most of them are caused by comet wakes. Meteors are traces of light produced by the friction and combustion of dust particles and solid blocks (meteoroids) in interplanetary space into the Earth's atmosphere. If they are not burned up in the atmosphere, they are called "meteorites" or "meteorites" when they fall to the ground. Meteoroids originally orbited the sun, and when they passed near the Earth, they were affected by the gravitational pull of the Earth and changed their orbits, thus entering the Earth's atmosphere. Many meteors radiate outward from a certain point in the starry sky (radiant), which is called a meteor shower.

Meteorites are the remnants of the largest meteoroids in the solar system that have not completely burned up after breaking into the Earth's atmosphere, and they bring us rich information about the formation and evolution of solar celestial bodies, and they are welcome guests. Every day, about billions, hundreds of millions of meteoroids enter the Earth's atmosphere, and their total mass can reach 20 tons.

meteorite

Meteorites: Earth often encounters small alien bodies. When these small bodies enter the Earth's atmosphere, they rub violently against the Earth's atmosphere and burn up. This is a shooting star. If a meteor falls to the ground before it has burned up, it is a meteorite. Meteorites are divided into stony meteorites, iron meteorites and stony-iron meteorites according to their main chemical components.

Their radius and mass are very different from each other and cannot be generalized. If the small object that hits the Earth is more than 10 kilometers in diameter, it will cause the same damage as the dinosaurs did back then. (To be continued.) )

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