The Great Conjunction of Jupiter & Saturn - 21st December 2020 ( A rare celestial spectacle last seen in 1623) 

The year 2020 is inching towards its closure and hopefully the Covid 19 pandemic, which has rampaged the world and taken away millions of lives including that of our dear friend, Vice Admiral Srikant will begin to fade away with the ever increasing number of vaccine candidates lining up to be introduced into the health care system. Fortunately there is a rare celestial spectacle - The Great Conjunction of Jupiter and Saturn - that is now getting played out in the evening sky and hopefully it helps us in diverting our attention from that singularity of Covid focus and lifts our spirits from the depressing news of Covid 19 pandemic. This celestial spectacle of the great conjunction of the Jupiter and Saturn,  which is getting enacted on the south western skies in most parts of India, is scheduled for its climax on the 21st of December - the winter solstice day. This will be one of the rarest of the rare celestial events that one can’t afford to miss more so since the last time such an incident happened was way back in 1623 and even this incident may not have been witnessed by people since the two planets were too close to the Sun. In that sense and realistically speaking the earliest previous instance of such a spectacular celestial event, which we will be witnessing on 21st December, occurred only in the year 1226. Therefore brace ahead and look up to the evening sky to get a glimpse of this spectacle.

The term Conjunction in the current context is used to describe the meetings of planets in our solar system. And when two of the largest planets in our solar system - Jupiter and Saturn, meet it is called the ‘Great Conjunction’, and on the 21st December we will be witnessing the Great Conjunction in our south western sky immediately after the sun set. The great conjunction happens thanks to the orbital paths of these two giant planets coming into alignment, as seen from Earth. It is well known that the Jupiter orbits our Sun every 12 years or so, while Saturn's orbit around the Sun takes nearly 30 years. This means that approximately every 20 years the two planets - Jupiter and Saturn, come into an alignment to form the Great Conjunction. However, it must be noted that although the Jupiter and Saturn planets will align about every 20 years and that the last such Great Conjunction in this century occurred in 2000, the Great Conjunction that will happen on the 21st December, 2020, will be the most spectacular of most of such Great Conjunctions between the two planets. Primarily because it is the closest observable great conjunction of the two planets for almost 800 years.

Therefore, let us all lift our spirit from that Covid conundrum, now that there seem to be light at the end of the tunnel both in terms of the falling rate of Covid cases and fatalities in India and so also the fact that scientists have managed to develop more than one effective vaccine candidates to combat this  pandemic.  Let us all, for the next week or so,  divert our attention from Covid to the Great Conjunction and focus on the rare celestial event and look to the South West sky every evening -  after sun set, from today to watch the two prominently visible giant gaseous planets - Jupiter and Saturn, of our solar system, inch closer and closer to each other until the D day - 21st December. On this day - 21st December, at around 11 PM Jupiter and Saturn will apparently appear as twin planets, which will be separated by a mere .07 degrees apart. This astronomical phenomenon, as stated above, is called the Great Conjunction, a relatively rare cosmic event. So please don't miss this opportunity to keep tracking these two planets in the evening sky every day, until December 21, 2020, when you will notice that Jupiter and Saturn will be a mere 1/5 of the moon-diameter apart. What an exciting moment it will be to watch this rare spectacle and hopefully the clouds will cooperate and not play spoil sport and deprive us of this unique opportunity. 

Like most planetariums and science museums and such other like minded institutions from across the globe, our Centre - Nehru Science Centre, Mumbai, too has been webcasting live telescope observation of this event for our esteemed audience, and has also organised two lectures on this subject and a very successful workshop. If any of you are priveleged to have a telescope, you can see in one view both Jupiter and Saturn and the three moons of Jupiter and one moon of Saturn in one single window of the telescope. This will truly be a momentous occasion for any one of us to see the Jupiter and its three moons and Saturn and one of its satellite in one window. To see this rendezvous, you will have to look towards the southwest sky immediately after the sunset to locate the more prominently visible planet Jupiter first and to its left will be a relatively less bright object -  the Saturn. 

The Brihaspati - Jupiter, the fifth planet in our Solar system, as stated above, takes nearly 12 earth-years to complete one full orbit of the Sun and the Shani - Saturn, the sixth planet in our Solar system, takes nearly 30 earth-years to complete one full orbit around the Sun. This means that both these giant gaseous planets - Jupiter and Saturn, come close to each other every 20 years. The next time these two planets will come close to each other will be in 2040. This celestial event is also called heliocentric conjunction. The super proximity between Jupiter and Saturn will be again visible after 60 years, i.e. 2080. When Jupiter overtakes Saturn while orbiting around the Sun, the two planets will be separated by more than a degree. But this December, the event will be different as they will be separated by just about one-tenth of a degree - almost nil.

Jupiter or Brihaspati is considered as Guru in Indian Astrology and is the largest planet in our solar system. Guru means one which is vast and great. In Hindu mythological texts all the major planets are called Navagrahas. The planet Jupiter - Brihaspati, has its own legend. The Navagrahas are worshipped as  Surya - Sun, Chandra - Moon, Mangala - Mars, Budha - Mercury, Brihaspati - Jupiter, Sukra - Venus, Sani - Saturn, Rahu and Ketu as Gods. There are dedicated temples for each of the Navagrahas and Alangudi temple in Tamilnadu is famous for Lord Brihaspati, where the lord Dakshinamoorthy is propitiated for Brihaspati and moola Shivalingam as the celestial power source for the temple. In this temple Lord Brihaspati is seen riding on a chariot pulled by eight horses and these eight horses are representing eight branches of knowledge.  Brihaspati is known as the Deva Guru of all Gods and also he is praised in Rig Veda.  Sani or Saturn is considered to be the son of Lord Surya and brother of Lord Yama. He has a chariot, or a buffalo or a vulture to ride. Sani has three hands holding an arrow, bow and javelin but the fourth one is in Varada Mudra. There is a famous Sani temple in Shingnapur, Maharashtra close to Nashik, where Lord Sani is worshipped in all his grandeur. 

Many in India are enamoured by these two giant planets - Jupiter and Saturn, now that there is an opportunity to look them up closely and literally as one, don’t miss it walk out and look up the sky to watch the great conjunction on the 21st December. Happy viewing.