Astromony question

1. Aug 2, 2005

asdf1

There's an astromony question that I'm stuck on~
" A distant galaxy in the constellation Hydra is receding from the earth at 6.12*10^7 m/s. By how much is a green spectral line of wavelength 500nm (1nm=10^(-9) )emitted by this galaxy shifted toward the red end of the spectrum?

2. Aug 3, 2005

neurocomp2003

what knowledge do you have?

3. Aug 3, 2005

Andrew Mason

Just use the relativistic doppler effect:

$$\nu_{obs}/\nu_{source} = \sqrt{\frac{1+\beta}{1-\beta}}$$

where $\beta = v/c = .204$ and $\nu_{source} = c/\lambda_{source}$

AM

4. Aug 3, 2005

asdf1

How did you think of to use the Doppler effect?

5. Aug 3, 2005

Nylex

Probably because the question is about the Doppler effect (well, it's about red shift, which is to do with the Doppler effect). Also, you mean "astronomy", not "astromony".

6. Aug 3, 2005

asdf1

I see~
Thanks for correcting my spelling mistake!