Galaxies seem to be made mostly of dark matter. One type of evidence for this comes from observations of
A) the redshift in the light from the explosions of distant supernovas.
B) the redshift in the light from the earliest galaxies in the universe.
C) Both of the above.
D) the speeds at which gas clouds orbit the centers of galaxies.
E) distant quasars.

Question

Quizplus · Accepted Answer

The speeds at which gas clouds orbit the centers of galaxies suggest the presence of unseen mass, or dark matter, because the observed speeds are too high to be accounted for by the visible matter alone.

Galaxies Seem to Be Made Mostly of Dark Matter