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5 Cards in this Set
- Front
- Back
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What are the 3 pieces of evidence for the existence of dark matter?
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1. Rotation of galaxies: rotating faster = more gravity = more mass we can't see (dark matter!)
2. Velocities of galaxies in clusters: calculating what we can't see = dark matter! 3. Gravitational lensing: light bends by gravity of clusters (distortion of light = more mass) |
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What percentage of all mass in the Milky Way is dark matter?
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85% Dark Matter
15% gas & dust |
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What do we think dark matter is?
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subatomic particles
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What types of variable stars are used as standard candles in measuring distance to galaxies?
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Cepheids (brighter than LL Lyrae stars)
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In addition to variable stars, what methods are used for measuring distances to galaxies?
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1. Parallax: (few 100 light years)
2. Tully Fischer: doppler effect of light 3. Hubble Law: correlation between red shift/distance 4. Type Ia Supernova: standard candle (same brightness); used to find expansion of universe is accelerating |
