Rotation curves for spiral galaxies show:
A)they are slowing down.
B)rotation speed drops off further from the nucleus.
C)most have dark halos.
D)most of the mass lies in the nucleus.
E)no relation to mass.

Question

Quizplus · Accepted Answer

The rotation curves for spiral galaxies show that the rotation speed does not drop off further from the nucleus as expected based on the visible matter distribution. This discrepancy can be explained by the presence of dark matter in the form of a dark halo surrounding the visible matter. Therefore, choice C is the best answer as most spiral galaxies have dark halos. Rotation curves for spiral galaxies show that the rotational velocity remains constant or even increases with increasing distance from the galaxy's center, which indicates the presence of additional mass beyond what is visible in the galaxy, also known as a dark matter halo. Therefore, most spiral galaxies have dark halos.

Rotation Curves for Spiral Galaxies Show