There is a grand conjunction of Jupiter and Saturn in the night sky on December 21, 2020. During such conjunctions, Jupiter and Saturn align on the same side of the Sun. Saturn and Jupiter are two of the largest massed planets in the solar system. Their combined gravitational pull impacts the location of the Sun. The combined gravitational pull of all planets impacts the Sun.
Scientists have known from sometimes that the gravitational center of the Solar system is not really at the center of the Sun. They called the gravitation center of the Solar system as the Barycenter. The Sun itself wobbles around this Barycenter. During the upcoming Saturn-Jupiter conjunction, the Sun will move its farthest from the Barycenter. Earlier this year, Scientists discovered a super-accurate way to determine the precise center of our solar system.
There is a story in the Puranas about the combined influence of all planets which they attributed to a pseudo planet called Gulikan. Ravana the Rakshasa king wanted all the planets to be at their peak positive energy when his Son was being born. This way his Son would be devoid of all negative planetary influences in his life. Ravana used his psychic powers to control all planets other than Shani or Saturn. He had to chopped off the feet of Shani to quell Shani. These feet became a reflective point in space. All the other planets contributed their energies into Gulikan. Ravana's son was defeated in a battle and died because of the adversarial position of Gulikan at the time Ravana's son was born. There are also interesting symbolism around Jyeshta Devi, Gulikan's mother.