If the above shown spiral galaxy is 150 million ly away, how fast is it receding?

Question

Quizplus · Accepted Answer

The galaxy is 150 million ly away, which means its light has traveled for 150 million years to reach us. According to Hubble's law, the recession velocity of a galaxy, v, is given by:

v = H0 x d

where H0 is the Hubble constant (about 70 km/s/Mpc) and d is the distance in megaparsecs (Mpc).

We need to convert the distance from ly to Mpc, which can be done using the fact that 1 Mpc = 3.26 million ly:

d = 150 million ly / 3.26 million ly/Mpc = 46 Mpc

Plugging in the values, we get:

v = 70 km/s/Mpc x 46 Mpc = 3220 km/s

Therefore, the correct answer is C.

If the Above Shown Spiral Galaxy Is 150 Million Ly