I want to measure the rotational speed of Io using a spectrograph, using the doppler formula. Since it is rotating around Jupiter, i have to take the velocity relative to jupiter, but I wonder tough how this is possible when Io is not rotating at an right angle to my observation point. Is there some mathematical way to solve this?(adsbygoogle = window.adsbygoogle || []).push({});

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# Io spectroscopy

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