1. Galaxies (Study Guide) (ES1-E) I know that our Sun is one of hundreds of billions of stars in the Milky Way galaxy. Many of these stars have planets orbiting around them. The Milky Way galaxy is one of hundreds of billions of galaxies in the universe.

2. Galaxies Galaxies are huge, and each consists of ________ of stars Galaxies are grouped together into clusters Clusters exist within _____________ Between each of these are huge regions of empty space.

4. Light Year One light-year is _________ miles (equals the distance that light travels in one year) Light travels at 299,792 _________ !!!

5. Galaxy Types Stars orbit in their galaxy based on the force of gravity. The stars in a galaxy give a galaxy its shape (setup by Edwin Hubble – 1926): -_________-________ -____________-________

6. Elliptical Galaxy Elliptical galaxies are ______ or ball- shaped

7. Spiral Galaxies Spiral galaxies are ________ -shaped with a bulging center and two or more _______ spiraling outward.

8. Barred Spiral Galaxies Barred spiral galaxies have a ________ of stars and arms that wind out from each end.

9. Irregular Galaxies ___________ galaxies have no particular shape.

10. Milky Way Galaxy It consists of at least _______ billion stars, one of which is our Sun. Our Sun is around 25,000 ________ away from the center and orbits every __________ million years. Believed to be a _________ ________ galaxy. It is about __________ light years across and _________ light years from top to bottom.

12. Local Group The Milky Way is part of a cluster of around 30 galaxies called the _________ _________ galaxy cluster. The largest galaxies in the Local Group are the Milky Way and the ____________ galaxy The Andromeda galaxy is one of the __________ spiral galaxies known. It is 2.4 million light years away.

13. What else is out there? ______________: gravity causes large amounts of mass to collapse inward so much that it becomes a hole in space. _________ _______: extremely dense small star, that has a solid surface ____________: neutron stars that send pulses of energy into space ___________: a cloud of dust and gas in space

14. Review: Identify the Photo Neutron Star Spiral Galaxy

15. Review: Identify the Photo Black Hole Barred Spiral Galaxy Nebula Elliptical Galaxy

16. Review: Identify the Photo Irregular Galaxy Pulsar