Home > Astronomy > Scale of Earth, Sun, Galaxy, and Universe

The apparent angular size of the moon is about 1/2 degree, how many full moons could fit across the apparent size of the Andromeda galaxy?

Answer 1

About #6#

The Andromeda galaxy has a diameter of roughly 140000 light years and is located approximately 2.5 million light years away from Earth.

Thus, it approximates subtends:

#(1.4*10^5)/(2.5*10^6) = 0.056# radians

That is, in degrees:

#0.056 * 180/pi ~~ 3.2^@#

So about #6# times the angle which the full moon subtends.

That being said, the Andromeda galaxy appears much smaller than it actually is because, under normal circumstances, we can only see its bright central region with a small telescope or the naked eye.

By signing up, you agree to our Terms of Service and Privacy Policy

Answer 2

Hailey Alexander

The apparent angular size of the Andromeda galaxy is about 3.1 degrees. Therefore, approximately 6 full moons could fit across the apparent size of the Andromeda galaxy.

By signing up, you agree to our Terms of Service and Privacy Policy

Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.