1. Astronomy- The Original Science Pages 4-10

2. A. Astronomy- the study of all physical objects beyond Earth

3. B. Calendar-a system for organizing time Aztec calendar Egyptian Stone calendar

4. 1) Calendars are based on movements of objects in the sky.

5. C. Year- time required for Earth to orbit the sun once

6. D. Month- amount of time required for the moon to orbit the Earth once

7. E. Day- the time required for the earth to rotate once

8. F. Many ancient civilizations developed calendars- Mayas, Chinese, Egyptians, and Hebrew

10. H. Julius Caesar fixed the problem of the seasons shifting due to the calendar by adding an extra day every 4 years- a leap year.

11. I. Most countries use the Gregorian calendar which scientists calculate will be accurate for another 3,000 years. It was created to make a year more accurate to 365.242 days per year by changing how often leap year occurs.

12. J. Early Observers NabtaStonehenge Babylonia ChineseMayan Building Ancient Arab- astrolabe

13. K. Early Astronomers

14. 1) Claudius Ptolemy- (Greek) Ptolemy thought that the Earth was at the center of the universe with the sun and other planets revolving around the Earth

15. 2) Nicolaus Copernicus- (Polish) thought the sun is at the center of the universe and the planets orbit around the sun.

16. 3) Tycho Brahe- (Danish)- used a mural which is a large quarter- circle on a wall to measure the positions of stars and planets.

17. 4) Johannes Kepler- stated that all the planets revolve around the sun in elliptical orbits and the sun is not in the exact center of the orbits.

18. 5) Galileo- was the first person to use a telescope to observe celestial bodies and discovered sunspots, 4 moons of Jupiter, craters and mountains on the moon

19. 6) Isaac Newton- explained that planets and moons stay in orbit due to gravity.

20. L. William Herschel discovered Uranus in 1781.

21. M. Edwin Hubble used photography in 1923 to discover that there are other galaxies.