Using an orbit size of 8 kpc, and a period of 225 million years, the mass of our Galaxy isfound to be closest to:
A) $10^6$ solar masses.
B) $10 ^ { 8 }$ solar masses.
C) $10^{10}$ solar masses.
D) $10^{11}$ solar masses.
E) $10^{12}$ solar masses.

Question

Quizplus · Accepted Answer

The mass of the Galaxy can be estimated using Kepler's third law, which relates the orbital period of an object to the mass of the object it orbits. In this case, the orbit size (semi-major axis) is 8 kpc and the period is 225 million years. When applied to the Milky Way, the calculations yield a mass of approximately $10^{11}$ solar masses, which is option D. This is a simplified explanation, as the actual calculation involves more detailed astrophysical equations, but the essence is that the mass of the Galaxy is sufficient to keep stars in their orbits at the given distances and periods.

Using an Orbit Size of 8 Kpc, and a Period 10610^6106

Using an Orbit Size of 8 Kpc, and a Period $10^6$