Suppose a scientist holds a press conference at which he claims that 10% of the matter in the Milky Way is in the form of dust grains. Does his claim seem reasonable? Why or why not?
A)The 10% figure is too high because there are not enough heavy elements to make that much dust.
B)The 10% figure is too low because most of the mass of the galaxy is in the form of interstellar dust.
C)It is reasonable because we already know that interstellar dust obscures our view through the disk of the galaxy.
D)It seems reasonable as long as we assume that red giant stars-which produce dust grains in their stellar winds-are more common than we thought.

Question

Quizplus · Accepted Answer

The 10% figure is too high because the majority of the matter in the Milky Way is in the form of dark matter and stars, with interstellar dust making up a much smaller percentage of the galaxy's total mass. Heavy elements, which dust grains are made of, are relatively scarce compared to hydrogen and helium, the primary components of stars and gas in the galaxy.

Suppose a Scientist Holds a Press Conference at Which He