History of Astronomy

1. History of Astronomy From this To this http://news.nationalgeographic.com http://www.spaceandmotion.com

2. Even prehistoric people looked at the sky and tracked the Sun, Moon and stars – the motion of these objects provided a clock and a calendar http://epod.usra.edu

3. Q 1: How do you think the sun, moon and stars can be used as a clock and calendar? http://apod.nasa.gov

4. A 1: The movement of the sun across the sky provides the time of day http://apod.nasa.gov

5. The length of a month was at first determined by the complete cycle of the moon’s phases

6. Calendar Chaos FYI • A year is 365.25 days • Tried to divide year by the lunar cycle (29.5 days)… 12 months of 29.5 days is 354 days! • The calendar we use now is from the 15th century

7. A year was determined by the movement of stars in the sky (rising in one location and taking a year to rise in the same location) July 5 http://www.astro.umass.edu/

8. http://www.astro.umass.edu/

9. Leap Year Interesting Info • A solar year is actually 365 days, 5 hours, 48 minutes and 46 seconds… • So we have an extra day every 4 years • Century years have a leap year only if they can be divisible by 400. (2000 – yes, 1900 – no)

10. Movements of the stars, Sun and Moon had religious explanations. The sky was a storybook. Stonehenge (UK) – 5,000 years ago Nationalgeographic.com

11. Q2: What stories, myths, etc… have you heard about the stars, sun and moon? http://www.webmousepublications.com

12. A2: Many cultures such as the Egyptians had sun gods. The Greeks had Helios who drove the chariot of the sun. There are stories about werewolves at full moons, people going crazy at full moons (lunatics). Full moons have names like Harvest Moon. http://www.webmousepublications.com

13. Over 4000 years ago the Mesopotamians named the oldest surviving constellations Nasa.gov

14. Q3: What are the names of some constellations? http://starryskies.com http://apod.nasa.gov

16. Q4: You do not need a telescope to see some planets. Which planets can you see with the naked eye? http://apod.nasa.gov/apod

17. http://apod.nasa.gov/apod

18. http://apod.nasa.gov/apod

19. The Ancients noticed 5 points of light that seem to wander among the stars – these were called planets by the Greeks.

20. Many ancient cultures used patterns in the stars to help them farm. Love-egypt.com

21. Q5: How can the stars help the ancient cultures farm? http://www.cartage.org.lb

22. A5: The location of the star in the sky can determine the season and let the farmers know when to plant seeds, when rivers would flood, etc. http://www.cartage.org.lb

23. The Chinese created an early calendar in 1300 BCE. They also observed supernovas and comets Astro.com

24. Ancient Astronomers were also astrologers – used the sky to tell the future and used rituals to prevent bad omens http://www.dailygalaxy.com

25. Q6: How do you think the zodiac signs were assigned to each month? http://www.lpi.usra.edu/

26. A6: The Earth goes around the sun, but ancient cultures believed the sun went around the Earth in a circle called the ecliptic. The sun’s apparent path was separated into 12 sections each assigned a constellation/sign. Whatever section the sun is in determines the sign of the zodiac. http://people.highline.edu

27. The Mayans and Aztecs associated the planet Venus with gods. • People in the Pacific Ocean used the stars to navigate http://www.mexconnect.com

28. Q7: How can you use the stars to navigate? http://globaloceanrace.com

29. A7: The position of stars such as Polaris (the North Star) can be used to determine direction at night. http://globaloceanrace.com

30. In 500 BCE the Greeks began explain the movements of the stars and planets based on math – not mythology http://cass.ucsd.edu

31. Astronomy • The scientific study of the universe and the objects in it (stars, planets, galaxies, moons). Astronomers study the positions, motions, distances, physical conditions (size, composition), origins and evolution of the objects in the universe.

32. 2 Vocab Words Geocentric: • Earth centered model of the solar system (planets, sun go around Earth) Heliocentric: • Sun centered model of the solar system (planets ALL go around sun)

33. Rotation The movement of an object turning on its axis (turning about itself) SPINNING

34. Revolution (in science) Movement of one object around another…

35. Rotation vs Revolution • Same: The Earth moves (in a somewhat circular path) • Different: Earth rotating: Earth spins on its axis, takes 24 hrs, Earth revolving: Earth moves around the sun, takes 365.25 days

36. Orbit The path an object takes while going around another object in space … so the path followed while completing a revolution Difference with Revolution: Orbit = all about the path Revolution = all about the motion

37. Day and Night • Day and night are caused by Earth’s rotation. • The side of the Earth that faces the sun has day; the side facing away from the sun is night. • Rotates from West to East.

38. If Earth Travels at a speed of 30 km/sec, how far does it travel in 1 year? 1 sec = 30 km (30km/sec * 1 sec) 30 sec = 900 km (30km/sec * 30 sec) 1 min = 1,800 km (30km/sec * 60 sec) 1 hour = 108,000 km (1800 km/min * 60 min) 1 day = 2,592,000 km (108000 km/hr * 24 hr) 1 month = 77,760,000 km (2592000 km/day * 30 days) 1 year = 946,728,000 km (2592000 km/day * 365.25 days) FYI: A spot on the equator rotates at 1,675 km/hr