Much of the mass of our Galaxy appears to be in the form of "dark matter" of unknown composition.At present,this matter can be detected only because
A) it absorbs light from distant galaxies and quasars and obscures them.
B) it emits synchrotron radiation.
C) its gravitational pull affects orbital motions of matter in the Galaxy.
D) it blocks out the light from distant stars in the plane of our Galaxy.

Question

Quizplus · Accepted Answer

Dark matter can be detected through its gravitational effect on the motions of visible matter in the Galaxy. This is observed through measurements of galactic rotation curves, gravitational lensing, and other methods. Dark matter does not absorb light or emit synchrotron radiation, so choices A and B are incorrect. Dark matter is not clustered in the plane of our Galaxy, so choice D is also incorrect.

Much of the Mass of Our Galaxy Appears to Be