Saturn took its name not from the planet on its logo, but from the Saturn rockets that sent man to the moon. Then-General Motors Chairman Roger Smith wanted to launch something new, and choose an appropriate name.
The metaphor behind the name also fits Roger Penske's decision not to move ahead with his plan to take over the Saturn brand.
GM had agreed to supply Saturn with vehicles for two more years. That would be enough to launch a new Saturn. But Penske needed another supplier of vehicles after that, and couldn't line up one.
Penske had the first stage of his rocket. But he wasn't going to launch without a second-stage booster rocket.