1. STARS

2. WHAT ARE STARS? CLICK ON THE PICTURE TO FIND OUT MORE

3. Think about it What are stars made of? How do stars differ from one another? Do stars move?

4. Composition of Stars A star is made of different elements in the form of gases. The gases in the atmosphere of a star absorb different wavelengths of light depending on which elements make up the gases. The light from a star indicates which elements make up that star.

5. Composition of Stars continued The Colors of Light A prism breaks white light into a rainbow of colors called a spectrum. An instrument called a spectrograph is used to break a star’s light into a spectrum. The spectrum of a star will vary depending on which elements are present.

6. Making an ID Emission lines are lines made when certain wavelengths, of light, or colors, are given off by hot gasses. Each elements produces a unique set of emission lines, which allows them to be used to identify the elements in a star.

7. Emission Lines of Elements

8. Classifying Stars Differences in Temperature Stars are now classified by how hot they are. Differences in Brightness The brightest star, Sirius, has a magnitude of -1.4. The dimmest star that can be seen with a microscope has a magnitude of 29.

9. Magnitude of Stars in Big Dipper

10. How Bright Is That Star? Apparent Magnitude The brightness of a light or star is called apparent magnitude. Absolute Magnitude Absolute magnitude is the actual brightness of a star.

11. Motions of Stars The Apparent Motion of Stars If you look at the night sky long enough, the stars also appear to move. The Actual Motion of Stars The apparent motion of the sun and stars in our sky is due to Earth’s rotation. But each star is also moving in space. Their actual movements, however, are difficult to see.

12. Apparent Motion of Stars Section 1 Stars

13. Actual Motion of Stars

14. CLICK ON THE PICTURE TO LEARN MORE ABOUT STARS

15. PUTTING IT TOGETHER  Pretend you are babysitting your 4 year old cousin. She is very curious about stars, and she wants to learn more. Write a dialogue between you and her where you explain everything you know about stars in a way that she could understand.