2. Astronomy
Phys 181

3. Readings: ASTRONOMY TODAY
Ch 23.1, 23.2
Ch 24.1, 24.2, 24.5
Ch 26
Readings

4. There was no "before" the beginning of our universe, because once upon a time there was no time. * John D. Barrow
I don't pretend to understand the Universe--it's a great deal bigger than I am. * Thomas Carlyle
A universe that came from nothing in the big bang will disappear into nothing at the big crunch. Its glorious few zillion years of existence not even a memory. * Paul Davies
Anyone informed that the universe is expanding and contracting in pulsations of eighty billion years has a right to ask, "What's in it for me?" * Peter De Vries Nothing puzzles me more than the time and space; and yet nothing troubles me less. * Charles Lamb
Quotes

5. Exam Review EXAM REVIEW
The final exam will consist of a choice of TWO (2) essays, selected by the student, from a list of FIVE (5) essay topics chosen by the professor.
Essays should be a minimum of FOUR (4) bluebook pages in length.
ESSAY TOPICS
Key discoveries in the history of Astronomy.
The role of Kepler’s laws in understanding the motions of the planets.
A comparison of the evolution of high and low mass stars.
A description of General Relativistic effects and their predictions regarding Black Holes.
Exam Review

6. Essays will be scored on the following criterion:
Coherence
Accuracy of information
Presence of four supporting arguments or evidence from the lecture or readings.
Presence of one referenced supporting argument or evidence from another source.
Conventional development: Thesis – Support – Conclusion
Reasonable grammar

7. Milky Way Galaxy

9. The Milky Way Galaxy: Vital Statistics
Diameter - 100,000 light years
Thickness (Nucleus) - 20,000 light years
Thickness (Disc) - 2,000 light years
Number of Stars - 200,000,000,000
Age - 15,000,000,000 years

13. The Halo

14. The Disk

15. The Core

17. Elliptical Galaxies 1/3 of all galaxies
Giant Ellipticals are the size of our galaxy but are rare
Dwarf Ellipticals are more common (6000 light yrs across)
Riesen-E

18. Spiral Galaxies
Largest fraction of galaxies
Andromeda

19. Barred Spiral Galaxy
NGC-1365

20. Irregulars
Large Magellanic Cloud

21. Galaxies form groups or Clusters
Coma Cluster

22. Olber’s Paradox

23. The universe is expanding!

24. Hubbles Law