To determine the orbital period of a visual binary, we must ...

[leo leo]

To determine the orbital period of a visual binary, we must measure
 
  a. brightness.
  b. position on the sky.
  c. wavelengths.
  d. luminosity.
  e. temperature.

Question 2

Increasing the diameter of a telescope I. increases its light-gathering power. II. increases its resolving power. III. increases it magnifying power. IV. increases its chromatic aberration.
 
  a. I, II, III, & IV
  b. I, II, & III
  c. I, II, & IV
  d. III & IV
  e. I & II

[ErinKing]

Answer to Question 1

b

Answer to Question 2

e

[leo leo]

Excellent

[ricroger]

Thanks for the timely response, appreciate it