UNIT VIII. THE RELATION OF OUR EARTH TO OTHER 



HEAVENLY BODIES 



The heavenly bodies have always been a source of 

 wonder to mankind. Early man observed the heavens 

 because he needed to know about them in order to 

 survive. The position of the sun in the heavens served 

 as his clock during the day, and the light from the 

 moon and stars guided him at night. Eclipses, com- 

 ets, and meteors were to primitive man evil signs of 

 the wrath of a displeased god. Even today there are 

 ignorant people who live in fear of such beautiful 

 phenomena in the heavens as comets and eclipses. 



As man became more civilized, he slowly accumu- 

 lated knowledge of the heavenly bodies and organ- 

 ized it into a crude form of science called astrology. 

 Astrology, which consisted of a body of facts mixed 

 with much superstition and fancy, flourished in 

 Babylon as early as 3000 B.C. and spread from there 

 to other regions of the ancient world. Today astrology 

 is no longer considered a science by intelligent people. 

 There are persons among us, however, who call them- 

 selves astrologers. They claim that they are able, 

 by observing the stars and planets, to foretell events 

 and to give sound advice in love, marriage, and busi- 

 ness. Most of these persons are frauds who are able 

 to make a living because superstitious people be- 

 lieve what astrologers tell them. 



Astronomy, the oldest of the sciences, had its begin- 

 nings in astrology. Astronomers, by years and years 

 of patient observation, have accumulated a large body 

 of knowledge of the heavenly bodies that enables us 

 to cast aside all our fears of celestial phenomena. 

 Today we look forward months and years in advance 

 to the exact second when an eclipse of the sun or 

 moon will occur. The mysteries of the comet and 

 meteor have been solved, and we await with delight 

 the return of a comet or the November meteors. 



The ancients, working with the crudest of instru- 



ments and only with the naked eye, discovered many 

 things about the heavenly bodies. Ptolemy, an Egyp- 

 tian who lived in the second century A.D., explained 

 the motions of the planets, but his explanations were 

 based upon a solar system with the earth as the cen- 

 ter. Centuries later Copernicus, a Polish astronomer, 

 conceived the idea that the sun is the center of our 

 solar system. In 1610 Galileo made the first telescope, 

 and with it came the era of modern astronomy. Since 

 then new and better telescopes and other marvelous 

 astronomical instruments have been built, and new 

 discoveries have followed rapidly. 



We live on a tiny speck in space acording to the 

 astronomers. Our sun is one of millions of stars and a 

 relatively small and unimportant one at that. Astrono- 

 mers believe that the universe of which our solar 

 system is a part is shaped like a watch and that it is 

 only one of many such universes which fill space. 

 These theories and facts about the heavens make a 

 most fascinating study. 



What do you know about the earth and other 

 heavenly bodies? Write the answers in your note- 

 book under the proper heading. 



1. How many changes does the moon appear to 

 make? 



2. What causes an eclipse of the sun? Of the moon? 



3. Who invented the telescope? 



4. What kinds of heavenly bodies can you name? 



5. What constellations do you know? 



6. Why do we have summer and winter? 



7. What is the evening star? The morning star? 



8. What is the name of the latest discovered planet? 



9. What is the difference between a star and a 

 planet? 



10. What is the Milky Way? 



TOPIC 1. LEARNING ABOUT THE STARS 



SUGGESTED PROBLEMS AND QUESTIONS 



1. How many stars can you see on a clear, 

 moonless night? 



2. What is a light year? 



3. What is the nature of the Milky Way? 



4. How large is our galaxy of stars? 



5. How many constellations are there? 



6. What is the nature of a star? 



7. How are telescopes constructed? 



SUGGESTIONS AND HELPS FOR STUDY 



1. In learning the constellations you will find it 

 helpful to have before you a map of the heavens for 

 that particular month. In Figure 285 you will find 

 maps showing the principal constellations in each 

 month of the year. After locating the constellation 

 on the star map, observe it in the heavens. 



2. Search the references for all the material which 

 you can find relative to planets, stars, and nebulae. 

 Astronomers have discovered some fascinating things 

 regarding them. 



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