In your own words, explain how astronomers determined that the ...

[strangeaffliction]

In your own words, explain how astronomers determined that the universe is expanding.
 
  What will be an ideal response?

Question 2

Topography and the upward and downward movements of cyclones and anticylones create ________ modifications of air masses.
 
  A) mechanical (dynamic) B) convective
  C) orographic D) thermal

[Meganchabluk]

Answer to Question 1

The best observation we can make to determine that the universe is expanding is based on the Doppler effect: the red shift. When we look at galaxies relative to each other, we can look at the light emanating from them. When this source of light is moving away from the observer, it is stretched, and this produces light of a longer wavelength. Longer-wavelength light is redder (shorter-wavelength light is bluer). Thus, by observing light shifting toward the red spectrum, we know it is being stretched, which in turn means it is moving away, which in turn means the universe is expanding.

Answer to Question 2

A

[strangeaffliction]

Excellent

[helenmarkerine]

Thanks for the timely response, appreciate it