A great conjunction is a conjunction of the planets Jupiter and Saturn. These Great conjunctions occur regularly (An average of 19.6 years) due to the combined effect of Jupiter’s 11.86-year (approximately) orbital period and Saturn’s 29.5-year orbital period.
The next great conjunction will occur on 21 December 2020. If you miss this conjunction today, then you could only be able to witness to wait and see Jupiter and Saturn this close together and higher in the night sky will need to stick around until March 15, 2080, Hartigan said. After that, the pair won’t make such an appearance until sometime after the year 2400. This will be closest conjunction ever since 1623.
One of those happened in 1623, but the sun’s glare made it impossible to see and the last recorded time of similar occurrence was in 1226. However, if you miss this upcoming very rare conjunction on Dec 21 – 2020, then you have wait for 60 Years (2080)
How to witness this conjunction:
Yes, Jupiter and Saturn are the biggest planets in the Solar System, But the distance between the Earth and the two planets is farther than the 4 times distance between the Sun and Earth. To our naked eyes, they’ll look like a single point of bright light. If you peek through a small telescope, Jupiter and Saturn will appear in the same field of view, along with some of their moons.
“In fact, they will be so close it may be a challenge to separate them with the unaided eye for many people,”
Best zone to see:
“Viewing conditions are best close to the equator, though no matter where you are, there is maybe an hour or so to observe this conjunction before the planets sink into the haze
For more details : https://sparky.rice.edu/~hartigan/public-night/jupsat.html