# Spectral lines

1. Nov 22, 2007

### mystery_witch

1. The problem statement, all variables and given/known data

How do you show that in spectra taken along the equator of a rotating rigid sphere the spectral lines are tilted but straight?

2. Relevant equations

There were no equations given in the problem, so I guess you can use whatever equations you know.

3. The attempt at a solution

From the Doppler equation

$$\lambda$$=$$\lambda_{0}$$$$\frac{\sqrt{1+\frac{v}{c}}}{\sqrt{1-\frac{v}{c}}}$$

you can see that you get a different result depending on if the velocity is towards us or away from us. I think this is enough to show that the lines would be tilted, but I'm not sure.
This is as far as I've come. I don't have any idea how to do the rest.