* Gaseous composition: They are all primarily composed of hydrogen and helium, with trace amounts of other gases and ices. This distinguishes them from the terrestrial inner planets (Mercury, Venus, Earth, and Mars).
* Large size and mass: They are significantly larger and more massive than the inner planets.
* Lack of solid surface: They don't have a solid surface like Earth, but rather a gradual transition from the atmosphere to their core.
* Multiple moons: All four outer planets have numerous moons, ranging from small rocky bodies to large, complex worlds with their own atmospheres.
* Ring systems: All four planets possess ring systems, though Saturn's are the most prominent and easily visible.
* Fast rotation: They rotate much faster than the inner planets, resulting in shorter days.
* Cold temperatures: Due to their vast distances from the sun, they experience extremely low temperatures.
These shared characteristics make them distinct from the inner planets and contribute to their categorization as "gas giants."
