It's too small to be a planet, it borderline doesn't have its own magnetic field because of how weak it is. Too weak to be a planet.
It isn't a star either because Unlike the Sun, which is a star, it doesn't produce light and heat, it just reflects it.
Anyway, to settle the matter the moon is actually an anticyclonic storm that broke off of Jupiter back when Adele's 21 was released. This is where the Great Red Spot comes from.