-1
$\begingroup$

I'm curious to know, does the sun really revolve around the black hole at the center of the galaxy?

$\endgroup$

marked as duplicate by Kyle Kanos, stafusa, Cosmas Zachos, sammy gerbil, ZeroTheHero Jun 11 '18 at 20:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

4
$\begingroup$

Sun revolves around the center of our galaxy. It takes about 225-250 million years (the timespan known as galactic year) to complete full circle. Taking this image from the wiki Sun galactic orbit

The center of the galaxy indeed contains the supermassive black hole. However the situation is significantly different from say the solar system. In the solar system almost all the matter is contained in Sun. The rest of the planets, moons, asteroids and comets contributes very little. So planetary orbits are determined mostly by Sun's gravity. In contrast the supermassive black hole in the center of our galaxy constitutes a miniscule proportion of the total galaxy mass. Also the significant part of the galaxy mass is in the dark matter halo which is spread even more than a visible matter. So saying that Sun revolves around supermassive black hole in the center is probably misguiding - its motion is determined mostly by other matter gravity.

$\endgroup$
  • $\begingroup$ Dark matter has not been detected. There are other explanations (like MOND) that do not require the existence of unobserved dark matter. $\endgroup$ – safesphere Jun 10 '18 at 8:59
  • 1
    $\begingroup$ MOND has been disproved because of gravitational lensing $\endgroup$ – Prada Jun 10 '18 at 17:00
  • 1
    $\begingroup$ Simple-minded modifications to gravity are ruled out several ways, which hasn't stopped people from wondering if there are more sophisticated ways to modify dynamics as an alternative to dark-matter. That approach is very much a minority preference, but it is not regarded as so far outside the mainstream as to taint ones career. But keep in mind that dark matter can explain not only galactic rotation curves, and cluster dynamics but also structure formation in the early universe which is more than any single modified dynamics theory has been able to accomplish. $\endgroup$ – dmckee Jun 10 '18 at 18:28
  • $\begingroup$ @safesphere Well, of course stupid scientists are attached to the stupid solution when there's obviously much more elegant alternative. Except that to produce MOND and fit all the observations you have to study rather pathological models that themselves introduce a lot of new fields that are yet to be observed. Please, if you want honesty, be honest to the end. $\endgroup$ – OON Jun 12 '18 at 11:36
  • $\begingroup$ @OON What a display of intolerance to alternative thinking, wow! Thanks for making it so clear. $\endgroup$ – safesphere Jun 12 '18 at 14:05
1
$\begingroup$

Geometrically the supermassive black hole , Sag A*, is at the centre of the galaxy. However, its 4 million solar masses contribute only a small part of the gravitational force of the billions of solar masses that keep the Sun in its orbit. Therefore, dynamically speaking, the sun does not revolve around Sag A* but around the total of this black hole of 4 million solar masses and billions of stars.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.