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Spiral galaxies are much more common in the centers of rich clusters than in the universe asa whole.
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Q67: An interaction between a large and a
Q80: In which of the following models will
Q81: The universe was two minutes old when
Q85: What use are 21 cm radio waves
Q88: In the lighthouse model:<br>A)pulsars are observable only
Q97: The period-luminosity relation is critical in finding
Q130: As a spaceship nears an event horizon,