1. Astronomy 201 The Sun and its Planets Dr. Jeff Kriessler

2. Discussion Come up with as many examples of products which are named after astronomical objects.

3. Discussion Come up with as many examples of how astronomy affects your daily life as you can.

4. Discussion What is a day? How would you define it to someone who doesn’t know anything about how we keep time?

5. Time Day – Time it takes the Sun to return to the same position above the horizon. Month – Time it takes the Moon to go through its phases. Year – Time it takes to move through the seasons. Note: Ancient definitions may differ from the modern usage!

6. The hour An hour originally was the time it takes the Moon to move its own diameter against the stars. Today we define an hour as 3,600 seconds where a second is 9,192,631,770 oscillations of a Cesium-133 atom.

7. “Fixed” stars and Planets Although the stars change their positions over the course of a night and from night to night, their relative positions (their positions relative to each other) remain constant year after year. Planet means “wanderer.” They change their positions relative to that of the fixed stars

8. The Planets of antiquity Sun Moon Mercury Venus Mars Jupiter Saturn

9. The days of the Week Sunday – the Sun’s day Monday – The Moon’s day Tuesday – Tiw’s day – Mars Wednesday – Woden’s day – Mercury Thursday – Thor’s day – Jupiter Friday – Freia’s day – Venus Saturday – Saturn’s day

10. Ordering of the day names Planets ordered by apparent length of period of revolution about a presumed stationary Earth: Saturn Jupiter Mars Sun Venus Mercury Moon

11. Assign each planet to an hour of the day: Saturn 1, Jupiter 2, Mars 3, Sun 4, Venus 5, Mercury 6, Moon 7, Saturn 8, Jupiter 9, … Which planet gets assigned the 25 hour? Discussion

12. Southern circumpolar stars

13. Total Solar eclipse

14. Total Lunar Eclipse

15. Ptolemy explanation for retrograde motion

16. Nicolaus Copernicus

17. Aristarchus explanation for retrograde motion

18. Tyco Brahe

19. Johannes Kepler

21. Galileo Galilei

22. Isaac Newton

23. Atom

28. Ceres

39. HST image 1995

40. Cassini

43. Ceres

47. Our place in the Universe Our Address: Case Western University Cleveland, Ohio USA Earth The Solar System The Milky Way Galaxy The Local Group The Local Supercluster The visible Universe

62. Visible Universe The portion of the Universe that light traveling at 186,000 miles per second, has had enough time to reach us. The visible Universe is a sphere with a radius of about 14 billion light years.

63. Hierarchy Universe – made up of lots of galaxies The Galaxies – made up of lot of solar systems The Solar System – where the influence of the Sun dominates over the influence of other stars