# Help in explaining a question on gravity

• B
Hello. I have this question: do you know why a physical body with bigger mass makes another one orbit around it like the sun does in the solar system and not the opposite of this? Thank you.

lomidrevo
The bodies actually orbit around the common center of mass.

You mean the sun also orbits around the center of the solar system which is different than the sun?

How is this explained mathematically? Do you know?

2022 Award
Google "barycenter". A planet orbiting a stationary Sun violates conservation of momentum because the Sun has zero momentum and the planet's momentum is changing. Both need to orbit a common center.

In the case of objects with large mass differences, the barycenter is very close to the center of the larger mass. So "Earth orbits the Sun" is close enough to the truth for most purposes.

• davenn
So saying heliocentric system is not correct, center of the solar system is correct which is not the sun. I understand now that they were approximations so far, scientists were trying to describe it and so far this is the latest correct view of the orbits of the solar system?

lomidrevo