QUESTION:
Pictures of Saturn show that it sort of flattens out near the poles and is wider at the equator. Why is that?

ANSWER from FAQ on June 11, 1999:
Indeed, Saturn's diameter pole-to-pole is only 108,000 km, compared to
about 120,000 km for the equatorial diameter. The difference is 12,000
km, which is about the diameter of Earth! The term for this is
"oblateness": The greater the difference between the polar and
equatorial diameters, the greater the oblateness. Saturn's rotation
around its polar axis is much faster than Earth's rotation. Saturn
rotates around once in less than half an Earth day (10 hours 39.4
minutes). This rapid rotation rate, combined with the planet's gaseous
nature tends to promote a bulge of material near the equator, and thus
the oblate shape. Even so, the oblateness of Saturn is less than would
be expected if it were composed only of hydrogen and helium. This has
led astronomers to believe that Saturn may have a massive rocky core.