In one of the rarest celestial event, Jupiter and Saturn will be seen very close to each other on Monday (December 21).

It will appear like one bright star.

On the night of December 21, their physical distance will be around 735 million kilometres.

According to NASA, after nearly 400 years since the planets passed this close to each other in the sky, and nearly 800 years since the alignment of Saturn and Jupiter occurred at night, as it will for 2020, allowing nearly everyone around the world to witness this "great conjunction."

The planets will next come close on March 15, 2080.

In most major cities across India, the conjunction could be seen just after sunset.