The mass of visible matter in a galaxy can be estimated by measuring its luminosity. When this is compared with the measured mass of the galaxy, astronomers find that ____.
A) the measured mass is about ten times the estimated mass, due to the effects of the central black hole
B) the measured mass is approximately equal to the estimated mass
C) there is no clear relationship between the estimated and measured mass
D) the measured mass is about ten times the estimated mass, due to the effects of dark matter
E) the estimated mass is about ten times the measured mass, due to the effects of dark matter

Question

Quizplus · Accepted Answer

The discrepancy between the mass of visible matter estimated from a galaxy's luminosity and its total mass measured through gravitational effects suggests the presence of dark matter, which does not emit light but exerts gravitational forces. This leads to the conclusion that the measured mass of a galaxy is significantly larger, often about ten times the estimated mass of visible matter.

The Mass of Visible Matter in a Galaxy Can Be