After 397 years: Jupiter-Saturn spectacle on December 21 set to wow stargazers

After 397 years: Jupiter-Saturn spectacle on December 21 set to wow stargazers.

The Covid-19 pandemic has completely disrupted life on earth. But celestial movements continue uninterrupted. And every once in a while comes a spectacle that has the ability to drive away all the earthly despondence and leave one in wonder and amazement.

The night of December 21 promises such an experience over the great conjunction of Jupiter and Saturn. The two planets will almost overlap each other — the closest they will appear in four centuries.“This will be the second-most close conjunction of Jupiter and Saturn since the invention of the telescope in 1609 by Galileo Galilei. The two planets have not been viewed this close to each other since 16 July, 1623,” pointed out M P Birla Institute of Fundamental Research director Debiprosad Duari. Prior to 1623, the closest observable Jupiter-Saturn conjunction was in the medieval times — in 1226.

December 23 also happens to be winter solstice in the northern hemisphere, the longest night of the year.

While a conjunction between Jupiter and Saturn occurs at an interval of 19 years and seven months, the proximity between them when viewed from earth varies and hasn’t appeared this close in 397 years. Jupiter takes 11.86 years to go around the sun once. The orbital period of Saturn is around 29.5 years.

A conjunction is an apparent phenomenon caused by the observer’s perspective: the two objects involved are not actually close to one another in space. Two celestial bodies visually appearing close to each other, as seen from the earth is called a conjunction. A conjunction of Saturn and Jupiter is called a ‘great conjunction’.

The once-in-a-lifetime super conjunction has sparked great excitement among sky lovers and enthusiasts. The next occasion when these two giant planets will come comparably close will be on March 15, 2080. But they will not appear this close.

Though the two planets will appear juxtaposed one on top of the other on December 21, their actual distance from each other will be around 735 million kilometres. In Kolkata, the conjunction can be viewed on the south-western horizon, between 5.28pm when the sun will set that day and 7.12pm when the two planets will disappear beyond the horizon.