What, if anything, does the solar system orbit?
1 Answer
The Solar System orbits the center of our galaxy, going around once roughly every 225-250 million years.
Explanation:
This time period is called a galactic year. It served as a convenient time scale for marking events in Earth's history https://en.wikipedia.org/wiki/Galactic_year).
The galactic year is also an important piece of empirical evidence for dark matter (https://en.wikipedia.org/wiki/Dark_matter), because of how short it is.
The Earth orbits the Sun in one year because that is how long the Sun's gravity takes to bend the motion of Earth into a closed curve given the relative speed of the Sun and the Earth and the distance between them.
Similarly, the accumulated gravity of the mass in the galaxy bends the Solar System's orbital motion into a closed curve in one galactic year. But in this case, the known masses of the stars is too little to bend the orbit as fast as we are seeing. Scientists believe that extra mass is present, but unobservable via electromagnetic radiation because it's transparent to such radiation. Only gravity interacts with it. This is the proposed dark matter in which the stars of our galaxy (and other galaxies) are embedded.
