Here's why:
* Methane is the dominant component of Titan's atmosphere. It makes up about 5% of Titan's atmosphere, compared to just a trace amount in Earth's atmosphere.
* Methane clouds form in Titan's atmosphere. These clouds are similar to Earth's water clouds, but they are made of methane instead of water.
* Methane rain falls on Titan's surface. The methane clouds produce rain that falls onto the surface, creating lakes and rivers of liquid methane.
While other planets and moons in our solar system have methane in their atmospheres, Titan is unique in having an atmosphere dominated by methane and experiencing methane-based weather.
