1. Star Systems and Galaxies
Section 15-4
Star Systems and Galaxies

2. Star systems and Planets
More than half of all stars are members of groups of two or more stars called star systems

3. Star systems and Planets
Double and Triple Stars
Binary System – two or more stars
Eclipsing Binary System – where one star covers the other
Found by looking at star “wobble” from gravitational pull of other star
Planets around other stars
Also found by looking at “wobble” caused by gravity

4. Galaxies Irregular Galaxies Spiral Elliptical Galaxies
Three types of Galaxies: spiral, elliptical, and irregular
Spiral
Pinwheel shape
Elliptical Galaxies
Shaped like a flattened ball
Irregular Galaxies
No particular shape, usually a cloud (very large nebula)