Thatsright
Answered

While a star is being observed through a telescope, the visible light coming from the star shifts from red to blue.

Which is true about this star? I know for sure it's either B or C

A.
The shortening of wavelengths indicates that the star is moving away from Earth.

B.
The lengthening of wavelengths indicates that the star is moving toward Earth.

C.
The lengthening of wavelengths indicates that the star is moving away from Earth.

D.
The shortening of wavelengths indicates that the star is moving toward Earth.



Answer :

AL2006
When the light ftom a star is observed at wavelengths shorter than they SHOULD BE, that indicates that the star is moving toward Earth. The wavengths don't shift while you're watching them. They're constant, at a wavelength shorter than they should be. The trick is how to know what the wavelengths of the light you're watching should be.