Dark Matter and the Mass of the Galaxy

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Quiz

Recently, astronomers discovered an object, 1999 DG8, that is out beyond the orbit of Pluto and may be roughly 100 meters across. It is the farthest Solar System object to ever be discovered, to date. Is it "dark matter?"

1: Yes
2: No
3: Maybe
4: I cannot tell.

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Can dark matter be yellow?

1: Yes
2: No
3: Only as yellow dwarf stars.
4: Only if it is moving toward or away from us to the extent that its light is shifted into the yellow wavelengths.

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What is the approximate mass of the observable part of the Galaxy (not including dark matter)?

1: 186,000 times the mass of the Sun.
2: 300,000 times the mass of the Sun.
3: 93 million times the mass of the Sun.
4: 100 billion times the mass of the Sun.

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Just considering Kepler's Laws, we would expect stars and other objects farther than the Sun from the core of the Galaxy to...

1: Orbit the core at a greater velocity.
2: Have a shorter orbital period than the Sun.
3: Orbit the core at a lower velocity.
4: Have the same orbital period as the Sun.

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What is the ultimate importance of the dark matter?

1: Friction with the dark matter slows the Earth in its orbit, ultimately moving us farther from the Sun.
2: The amount of dark matter helps determine how the Universe will end.
3: Dark matter shields us from cosmic rays from other galaxies.
4: Dark matter blocks our view of the core of the Galaxy.

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