Stellar and galactic crowding: The comparison of objects' sizes ...

[tsand2]

Stellar and galactic crowding: The comparison of objects' sizes to the distance between them gives a sense of their relative density, i.e., how crowded they are. A typical human is about 1 meter across the shoulders.
 
  Compare the relative density of people in the case where they are standing on average 1 meter apart compared to a situation where they are on average 10 meters apart (hint: describe the separation in units of person-size). Now, compare the crowding of stars to that of galaxies. A typical star has a diameter of about 1 million km, while the average space between stars is about 5 light-years. A typical spiral galaxy in a cluster (such as the Milky Way) is 100,000 light-years across, and has another spiral galaxy within about 10 million light years.

Question 2

Approximately how long did the nucleosynthesis era last?
 
  A) 10-10 seconds
  B) 5 years
  C) 5 minutes
  D) 0.001 seconds
  E) 5 seconds

[hanadaa]

Answer to Question 1

Students should reference the ratio of distance to size (or vice versa), to show that compared to their size, stars are much, much further apart than galaxies.

Answer to Question 2

C

[tsand2]

TYSM

[amandanbreshears]

Excellent