Question

Our solar system is roughly 2.28 x 10²⁰ m away from the center of the Milky Way galaxy, and the system is moving at roughly 227.7 km/s around the galaxy's center. Since most of the galaxy's mass is near its center (and we are on an outer arm of this spiral galaxy), let's model the galaxy has a spherical mass distribution (like a single, giant star that our system is orbiting around).

What is the mass of the galaxy (according to our rough, spherical model)? Obviously, this will be a VERY big answer, and so enter in your answer to the order of 10⁴⁰ kg. In other words, calculate the answer, and then divide by 10⁴⁰ and then enter in the result.

BTW - by assuming that all mass in the galaxy is made up of stars that are about the same mass as our sun, it isn't too hard to then estimate how many stars are in the galaxy!). As an another aside, some measurements and observations that we have taken in Astronomy suggests that in reality, stars only make up a fraction of the total mass (and there is something else that is also present that we haven't seen yet, and this mysterious mass is called: Dark Matter... but that is the story for another day). (Who this may concern could you please post the solution with step-by-steps so I can follow through to the solution. Thank you!)

Answer 1