How long is a day on Saturn? Universe Today provides simple answer: about 10 hours but varies by latitude. The article clarifies: "...researchers used information from NASA’s Cassini spacecraft, which has been orbiting the planet and its moons since 2004. The research challenge: Saturn is a gas giant full of layers that each have their own rotational speed. That makes it hard to figure out how long Saturn’s day is." Iowa undergrad, Tim Kennelly has studied phenomena known as Saturn kilometric radiation (aka auroral kilometric radiation) to gain further insight into seasonal changes and lengths of these "days" or periods. Now, you know how long a day is on Saturn.