1. Chapter 30 Section 1 Handout Characteristics of Stars

2. 1 What is a star? A ball of gases that gives off a tremendous amount of electromagnetic energy. A ball of gases that gives off a tremendous amount of electromagnetic energy.

3. 2 How does the color of stars seen from Earth differ from their actual color? From Earth, stars appear as tiny specs of white light, but they actually vary in color. From Earth, stars appear as tiny specs of white light, but they actually vary in color.

4. 3 How do astronomers learn about stars? By analyzing the light that stars emit. By analyzing the light that stars emit.

5. 4 What are spectrographs? Devices that separate light into different colors. Devices that separate light into different colors.

6. 5 What are the three types of spectra? Emission Emission Absorption Absorption Continuous Continuous

7. 6 What does a star’s dark-line spectrum reveal? The star’s composition and temperature. The star’s composition and temperature.

8. 7 What is true of the layers of a star? The inner layers are very hot The inner layers are very hot The outer layers are somewhat cooler The outer layers are somewhat cooler

9. 8 Elements in the outer layers of a star absorb: Some of the light radiating from within the star. Some of the light radiating from within the star.

10. 9 What do the colors and lines in the spectrum of a star indicate? The elements that make up the star. The elements that make up the star.

11. 10 What is the most common element in stars? What is the second most common element? Hydrogen (H) Hydrogen (H) Helium (He) Helium (He)

12. Matching 11-15 11. less than 3,500°C 12. 10,000–30,000°C 13. 3,500–5,000°C 14. 5,000–6,000°C 15. 7,500–10,000°C a. orange b. red c. yellow d. blue-white e. white See Page 776 Figure 2

13. 16 What is indicated by a star’s color? The surface temperature of the star. The surface temperature of the star.

14. 17 What color are the coolest stars? Red Red

15. 18 What is the diameter of the sun? 1,390,000 km 1,390,000 km

16. 19 Stars that are very dense may have: More mass than the sun and still be much smaller than the sun. More mass than the sun and still be much smaller than the sun.

17. 20 What two kinds of motion are associated with stars? Actual motion and apparent motion. Actual motion and apparent motion.

18. 21 What causes the apparent motion of the stars, which we can see with the unaided eye? The movement of the Earth. The movement of the Earth.

19. 22 What causes the circular trails of light seen in long-exposure photographs of the stars? The rotation of Earth on its axis. The rotation of Earth on its axis.

20. 23 In the Northern Hemisphere, the movement of stars called circumpolar stars makes them appear: To circle Polaris, the North Star. To circle Polaris, the North Star.

21. 24 What are three types of actual motion that stars may have? They rotate on an axis They rotate on an axis They may revolve around another star They may revolve around another star They either move away from or toward our solar system. They either move away from or toward our solar system.

22. 25 What is the Doppler effect? The apparent shift in wavelength of light emitted by a light source moving toward or away from an observer. The apparent shift in wavelength of light emitted by a light source moving toward or away from an observer.

23. 26 What does the fact that most distant galaxies have red-shifted spectra indicate? That those galaxies are moving away from Earth. That those galaxies are moving away from Earth.

24. 27 What is a light-year? The distance that light travels in one year. The distance that light travels in one year.

25. 28 How many kilometers does light travel in one year? 9.46 trillion km 9.46 trillion km

26. 29 When we witness an event on the sun, when did it actually take place? About 8 minutes before we see it. About 8 minutes before we see it.

27. 30 Except for the sun, what star is nearest to Earth? Proxima Centauri Proxima Centauri

28. The End