He determined the distance using a novel astrophysical method based on the observed rotational velocities of the galaxy and on the assumption that the luminosity per unit mass was the same as that of our galaxy .
The galaxy depends on the total mass around which stars are rotating .
He determined the distance using a novel astrophysical method based on the observed rotational velocities of the galaxy , which depends on the total mass around which stars are rotating , and on the assumption that the luminosity per unit mass was the same as that of our galaxy .