Caption: "In 2009 January and March, astronomers using NASA's Hubble Space Telescope (HST) took advantage of a rare opportunity to record Saturn when its rings were edge-on inclination, resulting in a unique movie featuring the nearly symmetrical light show at both of the gas giant planet's poles. It takes Saturn 29.4571 years to orbit the Sun, with the opportunity to image both of its poles occurring only twice during that time. The light shows are the Saturnian aurorae which are produced when electrically charged particles race along the magnetic field lines of the Saturnian magnetosphere and into the upper Saturnian atmosphere where they excite atmospheric gases, causing them to glow. Saturnian aurorae resemble the same phenomena that take place near the Earth's polar regions: i.e., the aurora." (Somewhat edited.)

Features:

1. The image is false-color---Saturn is NOT blue. It's sort of bland yellow overall with with faint bands parallel to its equator. There is no information with the image as to what wavelength band the image is in.

2. The rings of Saturn are aligned with Saturn's equatorial plane because the equatorial bulges cause an axisymmetric asymmetry in the gravitational field which favors said alignment.

3. The image clearly shows that Saturn is oblate.

4. The oblateness is caused by the centrifugal force due to Saturn's rapid axial rotation rate---Saturn's sidereal axial rotational period is 10.57 hours---and remember Saturn is big---it's equatorial radius is 9.4492 Earth radii.

5. Saturn's quatified oblateness is 0.09796 or nearly 10 %.

   The quantified oblateness is defined by the formula

         f=(a-b)/a ,

   where a is equatorial radius and b is polar radius.

   Loosely speaking, quantified oblateness is the fractional squashing.