| A | B |
|---|
| core | center of the sun where energy is produced |
| radiative zone | very dense region of the sun about 300,000km thick. |
| radiative zone | atoms in this zone are so closely packed together that it takes millions of years for light to pass through. |
| convective zone | region of the sun where gases circulate in convection currents |
| photosphere | the visible surface of the sun. Gases are thick enough to seen in this zone |
| chromosphere | deep, red zone; too faint to see unless there is a solar eclipse |
| corona | the outer atmosphere of the sun. it extends out to a distance 10-12 times the diameter of the sun. |
| AU - astronomical unit | the average distance of a planet from the sun |
| period of revolution | the amount of time it takes for a planet to go around the sun one time |
