Khan Academy Static

Galaxies are the basic building blocks of the universe. Even in a tiny patch of sky, many hundreds can be seen. By surveying such regions, astronomers estimate that there may be 100 billion galaxies in the observable universe. These galaxies are not uniformly spread through space--they commonly occur in pairs, groups, clusters, and superclusters. The articles and videos in this tutorial depict the different types of galaxies in our Universe, and the interactions between them. The final video in this tutorial looks at how one of the world's largest telescopes is bringing distant galaxies into view.

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