Why Do Rotation Curves of Galaxies Imply That Dark Matter

question 34

Multiple Choice

Why do rotation curves of galaxies imply that dark matter exists?

• A) The velocity of stars rises dramatically at large distances from the centers of galaxies,implying large amounts of dark matter cause these stars to move much faster than stars at smaller distances.
• B) The velocity of stars stays somewhat constant at distances beyond the visible edges of galaxies,implying that more matter than what we observe in stars and gas must be there.
• C) The velocity of stars is low in the inner regions of galaxies,suggesting that dark matter is impeding their motion.
• D) The velocity of stars rises quickly in the inner regions of galaxies,suggesting that unseen matter is gravitationally moving this material at faster rates than expected.

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