As We Look Deeper and Deeper into Space (And Thus

question 63

Multiple Choice

As we look deeper and deeper into space (and thus farther and farther back in time) ,the composition of rich clusters of galaxies

• A) is about the same mix of ellipticals and spirals that we find in the Virgo cluster and other nearby rich clusters.
• B) increases in the ratio of ellipticals to spirals.
• C) increases in the ratio of spirals to ellipticals.
• D) contains increasing numbers of large irregular galaxies,replacing spirals and ellipticals altogether.

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A potent greenhouse gas with a significant impact on global warming, more effective than carbon dioxide over a short period.

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