The Great Conjunction

By Parth Ghumare

We have all been enjoying the Jupiter-Saturn pair close-in beside the Milky Way core since the last year, and it is time for the climax now! 

On 21st of Dec 2020, this duo of the largest planets in our solar system will come extremely close to each other, and it will be, if anything, the most beautiful ‘double-planet’ our generation will see. The phenomenon of two celestial objects coming close to each other is known as a conjunction. But when the mighty Jupiter comes this close to the glorious Saturn, it is nothing short of the ‘Great’ conjunction.

The duo comes together in the sky every 20 years, and this happens when both the planets are aligned in a single line of sight as observed from Earth. This time though, the conjunction is an especially closer one and thus an extremely rare one. The Last time, these planets were this close was the year 1623 – only 14 years after Galileo started using his telescope – but it was too close to the Sun to be seen from Earth. Such a well observable conjunction of this splendor is estimated to have happened back in 1226. So, technically we can say that this is happening after almost 800 years!!!

The great ConjunctionIn the figure above, we can see the apparent distance between the two planets reducing over 2 months. This distance is expressed in degrees (written in blue). The great conjunction in the year 2000 had the two planets with a minimum approach of 13°. But this year, Jupiter and Saturn will be only 0.1° apart – and that is really close…. Closest we can ask for!!!

          To give you an idea of how small a tenth of a degree is, it is equivalent to a fifth of the diameter of the moon visible in the sky.

When observed through a pair of binoculars or a small telescope, Jupiter and Saturn will be visible with their respective moons – in a single field of view!!!! This is the biggest reason to be excited about it! An orange giant with stripes, and an ochre ball cradled by rings – with their moons adding to the scene – in a single frame. A once in a lifetime opportunity for the northern hemisphere to behold and Astro-photographers to capture.

Even though the closest approach is on the 21st, it is recommended to take a look at this duo every day, as, over the time between November 21 and December 21, Jupiter will travel about 6 degrees and Saturn 3 degrees on the sky’s dome. That movement will mean that Jupiter bridges the 3-degree gap between itself and Saturn. To notice them close-in so fast every day is mystifying in itself! So, keep an evening reminder on your mobile phones now to ensure that you won’t forget to take a look.

          Jupiter and Saturn are easily recognizable in the western twilight shortly after the sunset, from now through the end of the year. Jupiter is brighter than any other star and Saturn shines fairly bright with a distinctive golden colour, situated just to the east of Jupiter on the sky’s dome. Unlike the twinkling stars, Jupiter and Saturn both shine steadily.

          If you experience the building-up of this conjunction from today itself, you’re sure to be thrilled by the 21st of Dec. So, clear your schedule for 5 minutes daily post-sunset and keep your fingers crossed for clear, cloudless skies!  Happy stargazing!

 

 

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