Question

How fast does our solar system travel?

Answer 1

Hint: Recall that our solar system is housed in one of the spiral arms of the Milky Way Galaxy. The centre of the Milky Way galaxy imparts a gravitational influence towards all objects located in the galaxy directly or indirectly, leading to stellar systems orbiting around the galactic centre. In such a case, determine the velocity with which our solar system travels about the galactic centre, within the galactic frame of reference.

Complete answer:
Let us begin by establishing the location of our solar system, following which we shall deduce the velocity with which it travels in a suitable frame of reference.
We know that our solar system consists of our star, the Sun, and planets and moons orbitally bound to it by gravity. All planets, moons, asteroids, comets and meteoroids in the direct or indirect gravitational vicinity of the sun execute orbits around the Sun.
In the same way, the solar system, in its entirety, orbits around the centre of the Milky Way galaxy in which it is located. The solar system is located at about 26,500 light years from the galactic centre, about halfway along the Orion-Cygnus spiral arm of the Milky Way galaxy.
The duration of time required by the solar system to orbit once around the centre of the Milky Way’s galactic centre is called the galactic year or a cosmic year and is estimated to be around 240 million years. The solar system is thought to have completed 18-20 elliptical orbits about the galactic centre so far, and the orbital speed of the solar system is found to be approximately $220\;kms^{-1}$ or $0.073\%$ of the speed of light.
Thus, our solar system travels at about a speed of $220\;kms^{-1}$ relative to the centre of the Milky Way galaxy.

Note:
It is important to understand that the Milky Way, in addition to our Solar System, contains many more stellar systems in which planets orbit around stars. So far, about 500 stellar systems within our vicinity have been discovered across the Milky Way, each gravitationally bound to the galactic centre, travelling at various velocities depending on their location with respect to the galactic centre. Note that all velocities under discussion here are with respect to the Milky Way. Our universe consists of many more galaxies distributed in space but we do not know if they all in turn orbit around a universal centre. Thus, the speed with which the solar system travels through space would be different in a different frame of reference, if at all there existed any.