| A | B |
|---|
| Nebula | huge cloud of dust and gas that is the first stage of a star |
| Fusion | process by which the sun creates energy |
| Light year | how far it takes light to travel in one year |
| Sun | our star |
| Corona | the bright source of light seen on Earth |
| Chromosphere | boundary between sun and space |
| Photosphere | active layer; whre solar displays occur |
| Radiation Zone | where energy bounces back and forth |
| Convection Zone | cooler layer of gas rising and sinking |
| Core | the site of Hydrogen fusion |
| Sunspot | dark, cool spot on the sun |
| Galilleo | first astronomer to discover sunspots |
| Milky Way | spiral galaxy (the one we live in) |
| 3 Major Types of Galaxies | spiral, elliptical, irregular |
| Most Common Galaxy | elliptical |
| 200 billion | the number of stars our galaxy contains |
| Red | color of coolest star according to the Hertzsprung-Russell diagram |
| Galaxy | billions of stars in the same region of the universe |
