Explain how Edwin Hubble used Cepheid variables to change our ...

[cnetterville]

Explain how Edwin Hubble used Cepheid variables to change our view of the structure of the universe.
 
  What will be an ideal response?

Question 2

How does the Sun compare in size and brightness to other main-sequence stars?
 
  What will be an ideal response?

[jxjsniuniu]

Answer to Question 1

Cepheid variables are extremely bright variable stars that increase and decrease in brightness in a repetitive cycle. This group of stars is significant because their true brightness, called absolute magnitude, can be determined by knowing the rate at which they pulsate. When the absolute magnitude of a star is compared to its observed brightness, a reliable approximation of distance can be established. Thus, Cepheid variables are important because they can be used to measure large astronomical distances. Hubble observed the Andromeda galaxy, beyond the Milky Way, and used his observations to determine that the universe extended far beyond the limits of our imagination.

Answer to Question 2

It is a medium-sized, middle-of-the-road main sequence star.

[cnetterville]

Excellent

[xiazhe]

Thanks for the timely response, appreciate it