Our galaxy is suspected to be surrounded by a dark halo.What is it about the disk of the galaxy that makes us suspect this?
A)It rotates faster than expected in its outer region.
B)It rotates more slowly than expected in its outer region.
C)It is only visible during a total eclipse of our Sun.
D)It is surrounded above, below, and well beyond by the brightly glowing corona.

Question

Quizplus · Accepted Answer

Observations of the rotation of stars and gas in the outer regions of the galaxy have shown that they are moving faster than would be expected if the only mass present was the visible matter such as stars and gas. This suggests the presence of additional mass that cannot be seen, which is believed to be the dark matter halo surrounding the galaxy.

Our Galaxy Is Suspected to Be Surrounded by a Dark