One surprising result of the analysis of the properties of clusters of galaxies is that?

Question

One surprising result of the analysis of the properties of clusters of galaxies is that

a. the galaxies in each cluster appear to be moving away from each other, indicating that clusters probably came into existence in separate mini Big Bang explosions.

b. the mass of the easily visible matter (stars, and so on) appears to be insufficient to hold these systems together gravitationally.

c. each cluster is isolated from other clusters by a vast void that has probably been cleared out by the gravitational field of the cluster

Answer 1

B

the galaxy clusters rotate at greater speeds than they should, from analysis of the luminous matter within them and the virial theorem:

http://en.wikipedia.org/wiki/Virial_theo...

A is incorrect- galaxy clusters stay together as they have enouhg binding energy to resist cosmic expansion.

C is incorrect because clusters are not isolated by large viods (see the pic I linked to on your other question)

I am 100% sure this is the right answer

Answer 2

a) is nonsense.

b) is dubious

I'd put my money on c)

Are you supposed to already have been told the answer?

Answer 3

Have a look at this:

http://imagine.gsfc.nasa.gov/docs/featur...

and this (for fun)

http://imagine.gsfc.nasa.gov/docs/featur...