How do we know that galaxy clusters contain a lot of mass in the ...

[yoooooman]

How do we know that galaxy clusters contain a lot of mass in the form of hot gas that fills spaces between individual galaxies?
 
  A) The hot gas shows up as bright pink in visible-light photos of galaxy clusters.
  B) We infer its existence by observing its gravitational effects on the galaxy motions.
  C) We detect this gas with X-ray telescopes.
  D) We can observe the frictional effects of the hot gas in slowing the speeds of galaxies in the clusters.

Question 2

Kepler relied heavily on the telescopic observations of Galileo in developing his laws of planetary motion.
 
  Indicate whether the statement is true or false

[laurnthompson]

Answer to Question 1

C

Answer to Question 2

FALSE

[yoooooman]

Thanks for the timely response, appreciate it

[kjohnson]

Gracias!