China News Service, Guangzhou, December 17 (Guo Jun and Li Jianji) According to the prediction of the Wuyang Planetarium in Guangzhou, on December 21 this year (the winter solstice), the two largest planets in the solar system-Jupiter and Saturn will meet in Capricorn. The rare astronomical wonders that the readers almost "embrace" together.

If the sky is clear, after night falls, all parts of China can see this special celestial phenomenon with naked eyes.

If you use binoculars to observe, the effect is more ideal.

  The convergence of Jupiter and Saturn only occurs once an average of 19.86 years.

The last time they appeared on May 31, 2000, the two were 1.1 degrees apart, converging in Aries; the next time they would occur on October 31, 2040, they were 1.1 degrees apart, converging in Virgo.

The convergence of Jupiter and Saturn at 22:00 on December 21 this year is characterized by their very close distance, with an angular distance of only 0.1 degrees, which is only one-fifth of the full moon's apparent diameter (about 0.5 degrees).

Jupiter and Earth are so close, they are the closest since July 17, 1623.

If you want to see Jupiter and Saturn so close together again, you have to wait until March 15, 2080.

  Why does this special and rare celestial phenomenon occur?

Experts say this celestial phenomenon occurs when the Earth, Jupiter and Saturn are arranged in an approximately straight line.

In fact, this is just a perspective phenomenon. In fact, Jupiter and Saturn are about 650 million kilometers apart, which is about 4.4 suns from the earth.

From the perspective of the earth, if two celestial bodies move on the same right ascension, it is a double star meeting.

The planets revolve around the sun, Jupiter is 11.862 years, Saturn is 29.458 years.

Because Jupiter is close to the sun, it travels fast at an average of 13.06 kilometers per second; Saturn is far away from the sun and travels slowly at an average of 9.64 kilometers per second.

Therefore, the two had only one close-angle meeting in about 19.86 years.

  Recently, Jupiter and Saturn are in Capricorn, they are very close, and Saturn is east of Jupiter.

Jupiter is brighter than Saturn, and its apparent brightness is negative 2 magnitude.

Saturn has a magnitude of 0.6, which is brighter than the brightest star Altair (magnitude 0.76) in Aquila.

Jupiter is chasing Saturn from west to east (see illustration).

At 22:00 on December 21, Jupiter overtook Saturn, and both appeared on the same line of right ascension, and Jupiter was south of Saturn.

After December 21, Jupiter continues to orbit eastward, gradually moving away from Saturn.

  How to watch this rare encounter between the wood and earth binary stars?

Experts say that all parts of China (the observation conditions in the south are better than those in the north) can be found 25 minutes after sunset, and Jupiter and Saturn can be found at a low altitude in the southwest. The best observation time per day is only about 30 minutes and can be viewed for four consecutive days (December 20th to 23rd).

You can use a mobile phone or camera to shoot, and a telephoto lens is better for close-ups.

On December 21st, the sunset time in Guangzhou was 17:47, that is, Guangzhou was ready for observation at 18:12.

  On December 20, Jupiter will be west of Saturn, 0.2 degrees apart.

On December 21, Jupiter and Saturn will almost coincide. Saturn is north of Jupiter. Jupiter's light may submerge Saturn. You need binoculars or astronomical telescopes to "separate" the two.

On December 22, Jupiter will be east of Saturn, and the distance between the two will be greater than 0.1 degrees.

On December 23, Jupiter will be east of Saturn. The two will be 0.2 degrees apart, and the two will be farther apart day by day.

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