Saturn's spectrum is interesting for the chemical signature (Methane can be detected, for example), as well as the fact that Doppler Shift of the spectral lines allows some calculations to be made.

Note that most of Saturn's spectrum is simply a reflection of our Sun's spectrum.

Here is an example of how to use the Doppler Shifting of the lines to calculate physical data for Saturn:

The bright part in the center is the planet, and the dimmer parts above and below are from the East and Western side of the Ring system.

The "tilt" of the lines in the original high-resolution data, from one side of the planet's spectra to the other (i.e. not including the rings) appeared to be exactly one pixel.  Of course this is a very rough approximation but it's worth carrying the computation through.

Since the high resolution mode yields a dispersion of 1.07 Angstroms per pixel, we can translate that 1 pixel slant to a delta in wavelength of 1.07 Angstroms.

The basic non-relativistic Doppler formula allows a simple calculation of radial velocity as v/c = d(lambda)/(lambda).  I used 6563 Angstroms, the Hydrogen-alpha wavelength, for lambda.

However, the light from Saturn has actually traveled first from the Sun to Saturn and then back to us.  In addition, the tilt is being measured from both sides.  So the results need to be divided by two, twice.

Thus, v = (300,000 km/s * 1.07 Angstroms)/(6563 Angstroms * 2 * 2) = 12 km/s.

The more accurate figure per NASA is 9.6724 km/s.

There are of course numerous sources of error in the simple approximation calculated above, but this is still a fun exercise and the result is in the ballpark.