Do planets actually revolve around the sun? Maybe they follow the sun around a more central Star in middle of Galaxy? Based on the heliocentric model of orbiting, how could the planets revolve around the sun this way, if this it were true?
2 Answers
There is some truth in what you say, but some misunderstanding too.
Explanation:
No scientist seriously doubts the heliocentric theory, indeed evidence of it is available to anyone with a decent phone or very modest telescope and a few clear nights to observe the sky.
It is true however that all stars in our galaxy rotate around a common centre of mass, and that there is a central mass, a very large black hole, there. As a result the sun orbits in a complex 3D spiral about the galaxy, taking roughly 230,000,000 years to do so.
Several image on google (try searching 'Sun's trajectory around galaxy') show this better than I can describe it.
The Sun and the planets orbit around the centre of mass of the solar system.
Explanation:
It is not actually true to say that the planets orbit the Sun and the Moon orbits the Earth. The Earth and Moon both orbit around their centre of mass which is called the Earth Moon Barycentre (EMB).
Likewise the Sun and the planets orbit around the centre of mass of the solar system. This is called the Solar System Barycentre (SSB). The SSB is in constant motion and moves between the centre of the Sun and about a solar radius outside the Sun. The diagram shows the motion of the SSB over several decades.
The Sun also orbits around the centre of the galaxy. This is even more complex. In principle all of the stars will orbit around the centre of mass of the galaxy. This will be in the galactic bulge which contains a supermassive black hole.
The motion of stars in the galaxy is complicated by the fact that some stars, particularly on the edges of the galaxy, move in a way which gravity can't describe. There isn't enough visible mass to account for their motion.
It is now thought that galaxies contain a lot of dark matter. This interacts only through gravity and is otherwise invisible. We would need to know the mass and distribution of this dark matter to define what the Sun actually orbits around.
