Spiral arms appear bright because
A)they contain more hot young stars than other parts of the disk.
B)they contain far more stars than other parts of the galactic disk.
C)they contain more molecular clouds than other parts of the disk.
D)they are the only places where we find stars within the disk of the galaxy.

Question

Quizplus · Accepted Answer

Spiral arms appear bright because they contain more hot young stars than other parts of the disk. These young stars emit a lot of visible light, making the spiral arms stand out.

Spiral Arms Appear Bright Because