1. 30.3 Star Groups

2. Constellations Constellations:________________________ _____________________________________. Standard set of ____ constellations set by group of astronomers in 1930. –Acts as a road map to locate particular stars.

3. Naming Constellations ____________________________________ ________________________. Names come from… –Real animals e.g. Ursa Major, “The Great Bear” (The Big Dipper) –Imaginary animals e.g.Draco, “The Dragon” –Ancient Gods –Legendary Heroes

4. Multiple-Star Systems Binary Stars : __________________________ ______________________________________. Barycenter:____________________________ ______________________________________. Estimated that more than half of all observed stars are multiple-star systems.

5. Star Clusters _________: groups of hundreds or thousands of stars Globular Clusters:_____________________ _____________________________________. ____________: loosely shaped and rarely contains more than a few hundred stars.

6. Galaxies Galaxy:______________________________ ____________________________________ _______________. Major building blocks of universe Typical galaxy is 100,000 l.y. in diameter and contains 200 billion stars Estimated that universe_________________ __________________.

7. Types of Galaxies ______________________: has a nucleus of bright stars and flattened arms that spiral around the nucleus Elliptical Galaxies: vary in shape from nearly spherical to very elongated. Extremely bright in the center and have no spiral arms. Irregular Galaxies:______________________ _______________________________________ _________________________. More rare than other galaxies.

8. The Milky Way Spiral galaxy in which the sun is one of hundreds of billions of stars. ______________________________________ _____________________________. Takes sun 225 million years to complete one orbit. Closest galaxies are _____________away from Earth.

9. Quasars Discovered in 1963 ___________: quasi-stellar radio source; a very luminous object that produces energy at a high rate. Not related to star but related to galaxies. ______________________________________ ______________________________________ _____________________. Believed that black holes are present in those galaxies