Man's physical universe

xanabras

MANY INSTRUMENTS SUPPLEMENT TELESCOPE 79

considered as a mere stimulant to the imagination as, in the next

Section, we look out into space beyond our lens-shaped galaxy.

Fig. 14. Great Nebula in Orion. (Courtesy Mount Wilson Observatory.)

STUDY QUESTIONS

1. Explain how star distances are determined (1) by methods of parallax and

(2) by use of the spectroscope.

2. What are the Fraunhofer lines, and what is their significance?

3. What type of astronomical body is the sun?

4. Name two uses of the spectrometer.

5. What is the Doppler effect?

6. How is the composition of a star determined?

7. How is the intrinsic brightness of a star measured, and why is it needed in

measuring star distances?

8. How fast do the stars move?

9. How is the speed of the stars determined?

10. Describe the life cycle of the stars.

11. What is meant by the statement that many stars are multiple?

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