Why are most large telescopes reflectors, not refractors? A) ...

[future617RT]

Why are most large telescopes reflectors, not refractors?
 
  A) Large lenses deform under their own weight, but mirrors can be supported.
  B) Large mirrors need only one optical surface, achromats four surfaces to grind.
  C) Reflectors do not suffer from chromatic aberration like refractors do.
  D) Large, very clear lenses are harder to cast than more tolerant mirror blanks.
  E) All of the above are correct.

Question 2

How can we determine the reflectivity of an asteroid?
 
  A) by taking a photograph of it
  B) by measuring its mass and radius
  C) by comparing its brightness in visible light to its brightness in infrared light
  D) by where it is located in the asteroid belt

[sarahccccc]

Answer to Question 1

E

Answer to Question 2

C

[future617RT]

Thanks for the timely response, appreciate it

[Joy Chen]

Wow, this really help