Why do we believe there is dark matter? What will be an ideal ...

[jasdeep_brar]

Why do we believe there is dark matter?
 
  What will be an ideal response?

Question 2

What is thought to lie at the center of Jupiter?
 
  A) a hot sea of liquid metallic hydrogen
  B) gaseous hydrogen and helium, for Jupiter is not differentiated like Earth
  C) a fusion core like the Sun's, with hydrogen being turned into helium
  D) a solid core of crystalline helium
  E) a massive core of rocky materials with some iron mixed in

[SeanoH09]

Answer to Question 1

When we use the Keplerian equation to determine the mass of the Galaxy, we find a value of 100 billion Suns inside the Sun's orbital radius, or about 200 billion Suns all the way out to the end of the visible part of the spiral arms and halo stars. However, when we look the rotation curve, we find objects distant from the center rotating much faster than expected. To account for this, significantly more mass must exist outside the visible portion of our galaxy that we cannot see.

Answer to Question 2

E

[jasdeep_brar]

Thanks for the timely response, appreciate it

[gcook]

Gracias!