Here's why:

* Composition: Saturn's atmosphere is primarily composed of hydrogen and helium, just like the Sun.

* Density: Although these elements are very light, the immense pressure from the atmosphere's depth makes it incredibly dense.

* Depth: Saturn's atmosphere extends thousands of kilometers deep, far deeper than Earth's atmosphere.

In fact, Saturn's atmosphere is so thick that it's impossible to determine where it ends and the planet's solid core begins.