The figure below shows the rotation curves of several spiral galaxies,extending to the very edge of their visible disks.What do these curves tell us about the distribution of dark matter in these galaxies?
A) Most of the dark matter is in clumps.
B) Most of the dark matter is in the bulge.
C) Most of the dark matter is near stars.
D) Most of the dark matter is in the galaxies' outskirts.

Question

The figure below shows the rotation curves of several spiral galaxies,extending to the very edge of their visible disks.What do these curves tell us about the distribution of dark matter in these galaxies? 
A) Most of the dark matter is in clumps. 
B) Most of the dark matter is in the bulge. 
C) Most of the dark matter is near stars. 
D) Most of the dark matter is in the galaxies' outskirts.

Quizplus · Accepted Answer

The rotation curves show that the outer parts of the spiral galaxies are rotating faster than expected based on the visible matter alone. This implies the presence of additional matter, which we call "dark matter", and that it is distributed throughout the outer regions of the galaxies. Therefore, the most plausible explanation is that most of the dark matter is in the galaxies' outskirts.

The Figure Below Shows the Rotation Curves of Several Spiral