1. Star Systems and Galaxies Galaxies and the Big Bang Theory

2. Galaxies A Radio Telescope is a device used to detect long radio waves coming from objects in space. A galaxy is a huge group of single stars, star systems, star clusters,dust, and gas bound together by gravity The three different types of galaxies that exist in our universe are: Spiral Galaxies Elliptical Galaxies Irregular Galaxies

3. Spiral Galaxies The shape of a spiral galaxy is a bulge in the middle and arms that spiral outward like pinwheels Many bright, young stars Spiral galaxies contain gas and dust

4. Elliptical Galaxies Look like round or flattened balls Billions of stars Contain very little gas and dust between stars Old stars because little gas or dust and no stars are forming any longer

5. Irregular Galaxies Galaxy without a regular shape Smaller than other galaxies Many bright, young stars Lots of gas and dust to form new stars

6. Milky Way Our solar system is located in a spiral galaxy called the Milky Way.

7. The Expanding Universe Big Bang Theory –Universe formed in an instant –Billions of years ago –Enormous explosion Universe is expanding –Leftover thermal energy from the big bang is cosmic background radiation Evidence that supports the Big Bang Theory -Hubble studied the light spectrum of distant galaxies and observed that it shifted toward the red end of the spectrum -Hubble compared a galaxies’ spectrum to its distance and found a red shift (object moving away=longer wavelength (red)