The star Algol is a. an astrometric binary. b. a ...

[frankwu]

The star Algol is
 
  a. an astrometric binary.
  b. a spectroscopic binary.
  c. a visual binary.
  d. an eclipsing binary.
  e. a spectroscopic binary and an eclipsing binary.

Question 2

Which of the following features of a telescope determines its light-gathering power?
 
  a. the focal length of the primary lens
  b. the focal length of the eyepiece
  c. the diameter of the primary lens
  d. length of the telescope tube
  e. None of the other choices are correct.

[pami445]

Answer to Question 1

e

Answer to Question 2

c

[frankwu]

Great answer, keep it coming

[yeungji]

Thanks for the timely response, appreciate it