Describe the kind of observations that have led astronomers to ...

[jake]

Describe the kind of observations that have led astronomers to believe that supermassive black holes lie at the center of many galaxies.
 
  What will be an ideal response?

Question 2

Helium fusion does not begin until the star has entered the giant region of the H-R diagram.
 
  a. True
  b. False
  Indicate whether the statement is true or false

[jointhecircus]

Answer to Question 1

Measurements show that the stars near the centers of most galaxies are orbiting very rapidly. To hold stars in such small, short-period orbits, the centers of galaxies must contain millions or even billions of solar masses in a very small region.

Answer to Question 2

True