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Saturn's spin axis is tilted by roughly twenty seven degrees with respect to its orbit, allowing Earth-based observers to see its spectacular ring system partially open. It was not always like this, however. Astronomers believe that Saturn initially formed with no tilt and developed its non-zero obliquity at a later time. What tilted Saturn? Neptune! A long-range resonance between Saturn and Neptune first started in the distant past, but is ongoing today. Pushing someone on a swing is a good example of a resonance: if you want to make the person go higher you push with a steady rhythm, always at the same point of their back and forth arc. Similarly, the forces from Neptune pushed on Saturn at the same point in one of its natural cycles, resulting in an ever increasing tilt.