The Sun, which is `2.2 xx 10^20` m from the center of the Milky Way galaxy, revolves around that center once every `2.5 xx 10^8` years. Assuming each star in the Galaxy has a mass equal to the Sun's mass of `2.0 xx 10^30` kg, the stars are distributed uniformly in a sphere about the galactic center, and the Sun is at the edge of that sphere, estimate the number of stars in the Galaxy.

Explanation

To estimate the number of stars in the Milky Way galaxy, we can use the concept of gravitational force and centripetal motion. Here’s a step-by-step solution:

### Step 1: Understand the Problem
We need to find the number of stars (N) in the Milky Way galaxy, given the distance of the Sun from the center of the galaxy (R), the time period of revolution (T), and the mass of each star (m).

### Step 2: Identify Given Values
- Distance from the center of the galaxy (R) = \(2.2 \times 10^{20}\) m
- Time period of revolution (T) = \(2.5 \times 10^{8}\) years
...