What two observations allow us to calculate the Galaxy's mass?

Answer 1

By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.

By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.

By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.

By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.

Answer 2

By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.

Answer 3

Each planet has a gravitational influence on other planets, planetoids, etc. By observing their movements, the relative masses can be determined. Their relative distances are also fairly easy to determine, for example, by Kepler's Third Law. To know the absolute masses, two more items are needed: (1) a distance scale (convert the relative distances to absolute distances), and (2) the gravitational constant (look up information about the Cavendish balance).

Answer 4

1. The orbital velocities of stars and gas clouds in the Galaxy, which can be measured through Doppler shifts in their spectral lines.
2. The distance from the Galactic center to the Sun, which can be determined using methods such as parallax measurements or studies of variable stars.

Answer 5

its radius and its rotational velocity.

Mass = (Radius*rotational velocity)/G

G = The Gravitational constant = 6.673e-11 m^3 kg^-1 s^-2

Answer 6

The total mass of the Milky Way Galaxy is determined by its size and orbital velocity and just how much mass would be required gravitationally to maintain this velocity.