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Topic 1
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REVIEW: Lesson Summary
![[~]/perseus_star_cluster_jimkster_revised.jpg](/pluginfile.php/5394/mod_page/content/1/perseus_star_cluster_jimkster_revised.jpg "[~]/perseus_star_cluster_jimkster_revised.jpg")
Star cluster IC 348. Photo courtesy of jimkster/Flickr. Copyrighted,
non-commercial use allowed.
- The universe contains all the matter and energy that exists now, that existed in the past, and that will exist in the future. The universe also includes all of space and time.
- Redshift is a shift of element lines toward the red end of the spectrum. Redshift occurs when the source of light is moving away from the observer.
- Light from almost every galaxy is redshifted. The farther away a galaxy is, the more its light is redshifted, and the faster it is moving away from us.
- The redshift of galaxies tells us that the universe is expanding.
- The current expansion of the universe suggests that in the past the universe was squeezed into a very small volume.
- The Big Bang theory proposes that the universe formed in an enormous explosion about 13.7 billion years ago.
Last modified: Saturday, 24 April 2010, 9:27 AM