Astronomers can determine the amount of mass in a cluster of galaxies by observing its gravitational interactions. How much of this mass is luminous matter?
A) 1-2%
B) 10-20%
C) 50%
D) 80-90%

Question

Quizplus · Accepted Answer

The majority of mass in a galaxy cluster is actually dark matter, which does not emit light and is detectable through its gravitational effects. Luminous matter, which includes stars and galaxies that we can see, makes up about 10-20% of the total mass in a galaxy cluster.

Astronomers Can Determine the Amount of Mass in a Cluster