Astronomers think the Milky Way has spiral arms because
A) they can see them unwinding along the celestial equator.
B) radio maps show that gas clouds are distributed in the disk with a spiral pattern.
C) Pop II stars, hot molecular clouds, and asterisms outline spiral arms.
D) globular clusters outline spiral arms.
E) All of these choices are correct.

Question

Quizplus · Accepted Answer

Radio maps show that gas clouds are distributed in the disk with a spiral pattern, which is evidence for the spiral structure of the Milky Way.

Astronomers Think the Milky Way Has Spiral Arms Because