Introduction of Comet

Comets are special objects of the solar system and the majority of their orbit is a parabola, a small number of extremely narrow elliptical or hyperbolic, elliptical orbit of the comet, periodically appear near the sun. However, the long-period comet's orbit and the ecliptic plane any angle between.

Comets want to near from the sun will be found, rarely visible comet opportunity, when the forecast bright comet appeared comet observations of the general public, often provoked boom. About the size of the core of the comet within tens of kilometers, to attract the attention and it is really not a ratio.

Like the brightness of comets such as Comet Hyakutake, an average of every two, three decades a. Predict new is extremely difficult to find the next possible brightness of the comet, and only in accordance with past experience coupled with some imagination, were roughly the comet when the Earth is closest to the possible brightness. Comet Hale-Bopp (April 5, 1996), about seven hundred million kilometers away from Earth or about 5AU, its brightness is about 8.6 magnitude, according to the astronomers estimated luminosity curve development, 22 March 1997 day recently Earth distance, the luminosity of up to 0.4 magnitude, then likely will set off another wave of comet heat. Can see the comet in the Earth's night sky, please refer to the website of Comets and Meteor Showers.

The naming of the comet
Generally comet comet sub growth cycle (long-periodic comet) and short-period comets (long-periodic comet). The cycle is less than 200 years for the short-period comets, most of such comets orbit the same plane of the solar system. Long-period comet's orbit and the angle between the plane of the solar system, to any point of view, such as the angle of Comet Hyakutake is about 124 degrees, the Hale-Bopp comet, an angle of 89 degrees.

Besides named after the discoverer, the scientific name of the long-period comets (proper name) are named according to the year and month of the discovery by the International Astronomical Union (International Astronomical Union). International Astronomical Union annual twelve months subdivided into the first half and the second half of each of the 24 letters of the alphabet except "I" and "Z" calibration, such as Comet Hale-Bopp (a period of about 3,000 years) found On 23 July 1995, and for the second half of the first one discovered comet scientific name C/1995 O1. Comet Hyakutake (a period of about two million years) was found on January 30, 1996, is found in the second half of the second comet called C/1996 B2, it is learned. The short-period comets are often named after the name of the discoverer, such as Halley's Comet (cycle 76), known as P / Halley.



The nature and structure of the comet
Called comets as "dirty snowballs" or "dust ball" are quite appropriate. Comet far from the sun by the solar radiation, evaporation is not yet significant, referred to as the solid part of the comet nucleus (nucleus of), is mainly composed of dust, rocks, ice and condensed into solid ammonia, methane, carbon dioxide, etc. compounds.

The main structure of the comet nucleus, coma and tail. The size of the nucleus, which is normally in the tens of kilometers. The latest microwave radar data show that the the the Hyakutake comet's nucleus surprisingly small, ranging between one kilometer and three kilometers. The nucleus of Halley's Comet in about ten kilometers Schwassman-Wachmann, short-period comets nucleus as much as 40 km.

When the comet near the sun, by irradiation of the sun's light and heat, gas adsorption condensed substances and solid is evaporated, reflecting sunlight air mass formed in the nucleus peripheral called the coma (coma), nucleus and collectively known as the coma of the comet head. At this point, it sizes up to 100,000 km.

When the comet is very close to the sun, coma substances subject to solar radiation and the solar wind took its toll, forcing partial coma substances to deviate from the direction of the sun flowing, long hair-like tail (tail) tail is usually far from the sun, However, It is the Silk Book comet Figure, the shape of the coma and tail were highly variable, and tail can be subdivided into the dust tail (dust tail) and the ion tail (ion tail) in two parts. Tail length of up to several million kilometers or even hundreds of millions of kilometers long.

Tail material is also thinner than the laboratory vacuum, basically on Earth should not have any effect, but if any comet with Earth head-on crash, is another matter. 1908 in mysterious bombings in the forests of central Siberia (Tunguska event), many astronomers believe, is caused by a 50-100 m diameter comet or comet fragment exploded above the forest.