Which best describes the transit method? a. observing changes ...

[HCHenry]

Which best describes the transit method?
 
  a. observing changes in the brightness of the star when the orbiting planet crosses in front of the star
 b. observing the magnification of a distant star's brightness by gravitational lensing when an extrasolar planet passes precisely between Earth and a background star
  c. observing the back-and-forth motion that can be measured from Doppler shifts in a star's spectrum
 d. observing the intensity of brightness from a newborn distant star
 e. observing the magnification of a distant planet when it passes closely to our Solar System

Question 2

Explain why the current spectral classification letters are all jumbled and not in alphabetical order.
 
  What will be an ideal response?

[macmac]

Answer to Question 1

a

Answer to Question 2

The spectral classification sequence originated with the amount of hydrogen in the star's spectrum and was labeled A through Q. However, after plotting that information, it was noticed that there was no pattern to the graph. When they used temperature instead of the hydrogen line, the graph made sense, and has been adopted since then.

[HCHenry]

Thanks for the timely response, appreciate it

[momolu]

Great answer, keep it coming