17 December 2020

The Great Conjunction of Jupiter and Saturn - Dec 21st, 2020

We will witness a very rare and beautiful spectacle in the coming days. On December 21st, Jupiter and Saturn will be less than one-tenth of a degree apart from each other as seen from Earth, a rare alignment that happens only every 400 years at this extremely close separation. 

The Great Conjunction
Great Conjunction: Conjunctions occur often in the heavens, as heavenly bodies pass near each other, on in the less common scenario where the Moon covers stars and occasionally planets, and as planets and asteroids cover stars. In any case, a conjunction is usually a fascinating thing to see, particularly up close if you have binoculars or a telescope. When Jupiter and Saturn pass near each other every 20 years, we have a 'Great Conjunction' in which the two massive planets are very near each other. But every 400 years, the alignment is extremely good and we have both objects in one telescopic field of view, as portrayed in the image to the right. 

How to See It: The two planets will be visible only for a short while after sunset, and you will need a clear view to the west to see this. Look directly to the southwest of the point of sunset an hour after the sun goes down. If you have a telescope or binoculars, this is definitely the time to get them out and put them to work. If you can, look for the pair on Saturday 19th or Sunday 20th to get an idea where to find them. They will be in roughly the same place on the 21st, but through the telescope or binoculars the difference from one night to the next will be dramatic. 

Learn More: There are excellent articles online if you want to learn more about this rare and exciting event, on Scientific American or Earth-Sky. I find all of the detailed planetary geometry fascinating, and fun to understand how such alignments occur and can be accurately predicted. 

I wish you clear skies and happy viewing! 

Image courtesy Earth-Sky. 

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