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Star Groups 30.3. Constellations . Groups of stars that form a pattern in the sky 88 recognized by astronomers to divide the sky into sectors Appear to shift to the west a little each night due to revolution of earth so each season has a different set of constellations. Leo and Orion.
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Constellations • Groups of stars that form a pattern in the sky • 88 recognized by astronomers to divide the sky into sectors • Appear to shift to the west a little each night due to revolution of earth so each season has a different set of constellations
Galaxies • Large groups of stars bound by gravitational attraction • May be a trillion galaxies! • Avg. 100 LY wide with 100 billion stars per galaxy
Types of Galaxies Spiral Irregular Elliptical
Our Galaxy - The Milky Way • Cloudlike band across the sky • Spiral Galaxy- we are in one of the arms The sun takes 200 million years to revolve around the center
Star Clusters Globular Cluster - M80 • Galaxies also contain groups of stars • They can be open clusters or globular clusters
Binary Stars • Most stars in the galaxy are binary or multiple star systems • They revolve around each other