The Rotation of the Rings of Saturn Two spectra show that the two
handles of Saturn rotate. Maybe Saturn is surrounded by a disk or rings.
We took one spectrum at the left side and one at the right.
Instrument: The Gimp
The two circles show the projected fiber.
One spectrum is shifted about 2 Ångstroms against the other. This
shift is called Doppler shift and
allows us to calculate the speed of the rings.
Now we may do two exercises:
- Calculate the speed of the ring. Because we did compare the wavelength
of the left side of the ring with the wavelength of the right side and not
the ring with the body of Saturn, we must use the half value of our
shift. The light from the rings is reflected sunlight. We must divide your
result once more by 2.
- The mass of Saturn is MSaturn5.7×1026kg. With Newton's "Law of
Gravitation" we can calculate the radius of the path of a
body the Saturn at the calculated
speed from above. Does this radius lie within 80,000 km to
140,000 km the inner and outer radius of Saturns bright ring system?
- Fgrav =
- Frad =
- G = 6.67×10-11
Identification of the five lines:
The solar spectrum (black line) shows:
CaI at 6102.7 FeI at 6102.2 and 6103. We can not resolve these lines.
CaI at 6122.2
FeI at 6136.6, 6137.0 and 6137.7
CaI at 6162.2
CaI at 6169.0, 6169.6 FeI at 6170.5. Not resolved here.
The identifications are taken from Moore, Minnaert, Houtgast:
The Solar Spectrum.