Redshift measurements of a galaxy yield a recession speed of 1000 km/s. Hubble's constant H is 23-km/s/10⁶ ly. The distance to the galaxy is approximately A) 23 × 10⁶ ly. B) 37 × 10⁶ ly. C) 44 × 10⁶ ly. D) 52 × 10⁶ ly. E) 61 × 10⁶ly.

Question

Quizplus · Accepted Answer

The formula for Hubble's law is:
v = Hd
where v is the recession speed, H is Hubble's constant, and d is the distance to the galaxy.
Rearranging the formula gives:
d = v/H 
Substituting the given values, we get:
d = 1000 km/s / (23 km/s/10^6 ly)
Simplifying gives:
d = 43.48 × 10^6 ly ≈ 44 × 10^6 ly
Therefore, the answer is choice C.

Redshift Measurements of a Galaxy Yield a Recession Speed of 1000