Capítulo 125: CXXV. Ice Volcanoes.

Contrary to Saturn or Jupiter, descending into Titan's atmosphere was a much more clear and heterogeneous process of knowing when you were in space and when you eventually were inside of the moon's atmosphere, as the body was only a minimal fraction of the supergiants. 

In both of their previous visits, Cookie had wondered when both she and her companion were inside the gas giants and had already crossed over the layers of gas covering them, which were more vast and confusing than they appeared.

When you got close enough to those supermassive planets, you realized that the layers of the atmosphere that separated them from space weren't simple, divisible barriers, but rather gasses beginning to become denser and thicker, in a never-ending descend of clouds and tornadoes.

But Titan was another story. Although the moon's atmosphere was much denser than the one they saw on Mars, it was as if they were descending through the same corpse.