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looks at NASA's past, present, and future missions. It includes interactive tables and searches for earth, heliophysics, planetary, and astrophysics missions; information about dark matter and dark energy, planets around other stars, climate change, Mars, and space weather; science questions for NASA science missions; a "citizen scientist" page of resources to help citizens engage in scientific investigation; and expanded "For Educators" and "For Kids" pages. (National Aeronautics and Space Administration)
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In the early 1990's, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. |
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Merging galaxies |
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