What makes up the majority of the mass of an individual spiral galaxy?
A) A central supermassive black hole
B) Dark matter
C) Massive O- and B-type stars
D) Cold molecular gas clouds

Question

Quizplus · Accepted Answer

Observations show that the majority of the mass in a typical spiral galaxy is in the form of dark matter, which is a type of matter that does not interact with light or electromagnetic radiation and is therefore difficult to detect directly. This dark matter is thought to provide the gravitational glue that holds the galaxy together and allows it to rotate at the observed speeds. The other options - a central supermassive black hole, massive stars, and cold gas clouds - all make up a small fraction of the total mass of a spiral galaxy.

What Makes Up the Majority of the Mass of an Individual