The method the astronomer needs to find the distance is the hubble law.
The hubble law states that galaxies are moving away from at earth at speeds proportional to their distance.
The hubble law is expressed mathematically as v = H₀d where v = recessional speed, H₀ = Hubble constant and d = distance of galaxy from earth.
The recessional speed of the galaxy is found from the redshift of the light emitted from the galaxy.
Since we are dealing with a globular cluster of stars, the recessional speed is found from the redshift of the light emitted from the globular cluster of stars.
If we determine the recessional speed, we can then determine the distance of the globular cluster of stars by making the distance subject of the formula in the equation.
So, d = v/H₀
So, the method the astronomer needs to find the distance is the hubble law.
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