The client of Chinanews.com, July 16 (Reporter Shangguanyun) A few days ago, "The Big Comet is here" came on the hot search. Media reports said that a bright comet, numbered C/2020 F3, was passing the earth. It is reported that its observation conditions will become better in late July.
Zhu Jin, the honorary director of the Beijing Planetarium, said that "very bright" is one of the reasons why the comet has attracted attention. Such a large bright comet that is visible to the naked eye will occur once every ten years on average.
When will the comet observe better?
Generally speaking, a comet is a cloud-shaped object that surrounds or passes the sun. Most comets are relatively faint and bright enough to be seen with the naked eye.
On July 12, local time, in the Bahar ic-Caghaq village of Malta, comet NEOWISE can be observed in the local night sky. Image source: Visual China
Astronomers took pictures of comet C/2020 F3. As can be seen from the photo, the comet's "head" is very clear, and the comet's tail is relatively long and obvious, generally yellow-white.
"The comet numbered C/2020 F3 has two comet tails, one is a plasma comet tail, which faces straight away from the sun, and the other is a dust comet tail, which is slightly offset due to inertia." The National Astronomical Observatory Xinglong Observation Station Director Yuan Fengfang introduced.
She introduced that on July 22, the comet will reach perigee, about 103 million kilometers away from Earth. By the night of July 25th, the comet will appear on the horizon 30 degrees west-northwest.
"The comet numbered C/2020 F3 is very bright, especially for the northern hemisphere, it has not been seen so bright for a long time. This is also one of the reasons for its attention." Zhu Jin said that the observation conditions in late July will be more better.
What is the structure of the comet?
Generally speaking, a comet consists of two parts, the head and the tail. Comet heads generally include comet nucleus and coma. Comet nucleus is the most central and main part of comet.
Data Map: According to Reuters report on April 20, an interstellar comet named "2IBorisov" traversed the solar system. This comet may not exceed 975 meters in diameter, and when it approaches the sun, gas is ejected from it. (The picture is a composite photo)
Zhu Jin said that compared with asteroids, the comet nucleus is generally small in size, and some may be only a few hundred meters in diameter. From an observation point of view, the coma nucleus is a bright spot when people look at the earth from afar. With a coma, a comet will appear fatter than a "star point".
"There are many projects in the astronomy field to search for asteroids, and many comets were discovered during this process." He said that the comet numbered C/2020 F3 was discovered by the NEOWISE satellite, so it is also called the NEOWISE comet.
What are the types of them?
Regarding the origin of comets, Zhu Jin introduced that there is a saying that there is a large comet zone in the outer periphery of the solar system, called the Oort cloud. "There are a lot of comets inside, but almost all are far away from the sun."
Comet's orbit has ellipse, parabola, hyperbola. Zhu Jin said that it is currently believed that those with an orbital period of less than 200 years are generally called periodic comets, and those with a period of more than 200 years are generally called non-periodic comets.
For example, Zhu Jin said that Halley’s comet is a periodic comet with a period of 76 years.
Because the name carries the word "star", occasionally someone will confuse comet and meteor, but the two are not the same thing. Zhu Jin explained that the comet can usually be seen for a long time; as for the meteor, it is because the meteor body will emit light when it enters the atmosphere of the earth, which is basically "fleeting."
Comet doesn't shine by itself?
Interestingly, although the comets in the photos are basically "shiny", the comets themselves do not emit light.
The picture shows the exploration effect of comet probe. In 2014, the European Space Agency announced on January 20 that the European "Roseta" comet probe woke up as planned at 10:00 GMT (18:00 GMT) and continued to pursue "Churyumov-Gerasimenko" Comet, the Earth Control Center is expected to receive the first signal from the probe after 7 and a half hours.
According to reports, when the comet is close to the sun, due to the influence of solar radiation pressure and temperature changes, dust is emitted. This dust reflects sunlight.
Zhu Jin said that the level of ancient science and technology is backward. When the ancients saw such a large and bright comet appearing in the sky, it was often difficult to understand, and a series of superstitions were produced. From a scientific point of view today, ancient superstitions simply do not hold water.
"Observation and visible to the naked eye are two concepts. Through telescopes and detectors, the number of comets that can be observed by humans is much larger than the number of comets that can be seen by the naked eye. It is not uncommon for a few comets to be seen by the naked eye." Zhu Jin said . (Finish)