This year, at the winter solstice, we will have the opportunity to admire the precious moment of meeting after nearly 800 years, so as not to miss this event, please refer to the article below!
Astronomers use the word “conjunction” to describe the meeting of planets and other celestial bodies on the celestial sphere. In this document, the term “great conjunction” is used to refer to the meeting between the two largest planets of the solar system – Jupiter and Saturn. On December 21, the conjunction of Jupiter and Saturn will take place. It will certainly be the most significant event in the western sky after sunset. On December 21, the pair will be only 0.1 degrees apart and some say it looks like a star stretched across the sky.
History of the great conjunction between Jupiter and Saturn
Jupiter-Saturn conjunctions occur every 20 years, the most recent dating from 2000. But not all of these conjunctions are equal. Conjunction 2020, these two giant planets will make their closest rapprochement since 1623 and the closest observable in 1226. The Jupiter-Saturn conjunction will not occur once again before March 15, 2080.
Why does the Jupiter-Saturn conjunction occur every 20 years?
Both Saturn and Jupiter move quite slowly and take many years to complete a full circle around the Sun: Saturn takes 12 years and Jupiter takes nearly 30 years. This means that Saturn will only complete 12 degrees of its orbit around the sun each year, while Jupiter will complete 30 degrees. Therefore, each year Saturn will be approximately 18 degrees from Jupiter (30 – 12 = 18 degrees). Thus, every 20 years, these two planets will be separated by exactly 360 degrees (18 x 20 = 360 degrees), which means that by observing in the sky, we will see them crossing each other.
General Assembly 2020
This year, since November, Saturn and Jupiter are getting closer and brighter in the night sky, they are only 3 degrees apart. Jupiter will soon catch up with Saturn and we will have a beautiful conjunction. The event will take place on December 21, 2020. It is a coincidence that the event coincides with the winter solstice. This is the first time that Saturn and Jupiter have been conjoined since 2000. However, this conjunction is very special because Saturn and Jupiter will be only 0.1 degrees apart. The last time Saturn and Jupiter were this close was nearly 800 years ago.
Saturn is the 6th planet from the Sun and the 2nd largest planet in the solar system. Jupiter is brighter than any star in the sky, while Saturn shines with a distinctive golden glow. These two planets are visible to the naked eye. Although the two planets appear spectacularly close to each other in the sky, in reality Jupiter and Saturn are more than 700,000 km apart.
The positions of Jupiter and Saturn on the days of peri-conjunction. Photo: Sebastien Voltmer
How to observe the great meeting of Moc – Tho?
According to NASA, to be able to observe this event, you must look southwest one hour after sunset. If you miss this chance to see it, you will have to wait until 2080 to see a great conjunction with two planets so close to each other.
Jupiter is brighter than any star in the sky. Although less luminous than Jupiter, Saturn shines like the most prominent stars with a characteristic golden glow. At this time, Saturn will be east of Jupiter in the sky, both recognizable by their apparent brightness and proximity.
Additionally, the New Moon at the beginning of the month will also appear in the West with the two planets, creating a beautiful moment that graces the winter sky.
The meeting between the two planets and the Moon on December 17, 2020. Photo: Alireza Vafa
Hanoi Amateur Astronomical Society (HAS)
Translator: Hue Le (HAS translation team)