Solar+System+Unit+Key+Words

2. galaxy page 596 3. rotation page 630 4. revolution page 630 5. astronomical unit page 645 6. terrestrial planet page 648 7. prograde rotation page 649 8. retrograde rotation page 649 9. gas giant page 654 10. satellite page 660 11. phase page 662 12. eclipse page 663 13. comet page 668 14. asteroid page 670 15. asteroid belt page 670 16. meteoroid page 671 17. meteor page 671 18. geocentric model of the solar system Page 555 Ancient people thought that the earth was at the center of the solar system, and that all other objects orbit around the earth.This was introduced by Ptolemy. || 19. heliocentric model of the solar system page 555 A polish astronomer named Copernicus introduced the theory that the sun is at the center of the solar system. 20. orbit page 630 21. year page 554 22. month page 554 23. day page 554 24. Milky Way Galaxy page 597 25. Solar Eclipse page 663 26. Lunar Eclipse page 664 ||
 * 1. Big Bang Theory Page 601