Here’s a simple question: how long is a day on Saturn? The answer, it turns out is very complex. Cassini recently measured its day at just over 10 hours and 45 minutes, but this is a full 6 minutes longer than the Voyager spacecraft measured. If this is correct, Saturn has slowed down 1% in only 23 years. Length of day is usually measured by a radio telescope, watching as the magnetic field sweeps around. With Saturn, however, it looks like the planet isn’t locked to its magnetic field, which can slip around to different latitudes.