1. 

• Read the week 6 instructor notes for a discussion of different distance measuring methods (including the term 'standard candle') in astronomy. 
• For images (& explanations) of what the Milky Way galaxy looks like in a wide variety of wavelength of light, go to the following list of images.
• For an excellent, easy-to-read review of what research astronomers think about the formation and evolution of galaxies (including their supermassive black holes, their stars, and their dark matter), go to the following websites:
  http://www.space.com/scienceastronomy/blackhole_history_030128-1.html
  
  Also pertinent to galaxy evolution is the latest information about the rate of star formation in the past.  For a summary, see the following link:  http://skyandtelescope.com/news/article_1235_1.asp
• For some links to information about galaxy evolution, including mergers and dark matter considerations, go to the following week 6 galaxy evolution supplement .
• For a summary of recent extremely strong evidence supporting the hypothesis of a central supermassive black hole at the center of the Milky Way Galaxy, go to the following URLs:
  http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html
  http://antwrp.gsfc.nasa.gov/apod/ap021018.html
  http://chandra.harvard.edu/press/01_releases/press_090501flare.html
• The APOD story on February 12, 2004 is about discovery of a surviving companion star to a massive star whose core collapsed, leading to explosion of the massive star.   In the 250 years before the explosion, the massive star transferred 10 solar mass to the survivor.  The explosion, which occurred in 1993 in the spiral galaxy M81 (in Ursa Major, about 12 million l.y. distant), has been well-known for the lack of hydrogen lines in the debris spectrum; yet, it was not a type Ia supernova.  Now we know why.   Astronomers also had pre-existing images of the massive star before explosion, which makes this supernova only the second (after SN1987a) case in which images exist of a star before it exploded.  For the complete story, see the following URL:
  http://hubble.esa.int/science-e/www/object/index.cfm?fobjectid=34455
  or, for the apod short story:  http://antwrp.gsfc.nasa.gov/apod/ap040212.html
• This link takes you to a story of the relatively recent (1994) discovery of the closest galaxy to our Milky Way (until someone discovers another dwarf galaxy even closer?) - the Canis Major galaxy.  http://antwrp.gsfc.nasa.gov/apod/ap071104.html
• Here's a report (June 2008) on recent studies of our Milky Way galaxy, based on long-wavelength studies of our galaxy over the past several years.  Some of the description of our galaxy is a little different than in present-day textbooks.
  http://antwrp.gsfc.nasa.gov/apod/astropix.html

3. week 6 homework Print out and circle your answer choice for each question.  I'll take questions about these during class time.   Turn these in the first day of week 7.