The fantastic planet Saturn is in good observing position these days. Not quite to opposition but it's getting close.
I'm hoping to work on imaging it soon with an inexpensive webcam. Meanwhile, here are a couple of spectra that I took of Saturn recently, along with an old image taken last year with an LPI. Click here to see a larger version along with more information about this data.
For this project, I placed the slit along the equator and across the rings. This results in a spectrum consisting of 3 general regions: the Eastern side of the rings, the planet itself, and the Western side.
Saturn's spectrum is really primarily the spectrum of our own Sun, reflected back. But due to the rotation of the planet and rings, a pronounced tilt in the spectral lines occurs. This tilt can actually be used to calculate some data about Saturn and the rings.
For example, by measuring the tilt and using that information along with the dispersion of the spectrograph (in this case, 1.07 angstroms per pixel), I can calculate the rotational velocity of the planet and the rings. My quick and preliminary calculations resulted in a value of 12.2 km/s; the accepted value is about 10 km/s.
This is a fun little project and I'll probably try to refine it in the near future along with the next imaging attempt. Of course calculating the rotational velocity of Saturn isn't really valuable science, since NASA has the market covered pretty well on that topic. But for personal exploration and satisfaction, it's a lot more fun to try to determine things like this on my own that it is to look up a number in some reference book or website.
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