I am to measure the rotational velocity of Io relative to Jupiter, and will do so using a spectrograph.(adsbygoogle = window.adsbygoogle || []).push({});

I will measure the frequency change of a specific mineral emmision band in the spectra, and then check how much it has shifted from its original wavelenght with a table. Then I use the formula:

[tex]v = (\Delta \lambda/\lambda) c[/tex]

where [tex]\Delta \lambda[/tex] is the change of frequency and [tex]\lambda[/tex] is the rest wavelenght. C is speed of light.

to calculate the velocity for each object.

The problem is how do I calculate the velocities relative to each other? Io rotates around jupiter, using my method i believe i can only calculate its speed moving relative to earth?

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# Homework Help: How to calculate relative doppler shift

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