英语听力：自然百科 行星旅行：土星 Saturn—15（在线收听）

In fact, as we took radar pictures of other parts of Titan, we found even wilder things in the northern polar areas. There are entire lakes, or even seas, that look/ to all the world like you could go take a boat and go do jet skiing or something, right, you know, up and down these sea channels there.

Titan is the only other place in the solar system that we know liquids exist on the surface. So here you have vast reservoirs of liquid natural gas and oh, by the way, we have thrown in some ethane, which is slightly more complex hydro-carbonate, oh, by the way, there are some propane in there. Everybody knows what propane is, you use it in your backyard barbeque. 

Cassini's radar spied / lakes as biggest inland seas, even bigger than Lake Superior. Imagine standing on the shoreline of what to you looks like an ocean of liquid hydrocarbons. That's gotta be pretty special. 

And if you think the lakes are weird, try the volcanoes.

We think the material that comes out of Titanian volcanoes is a mixture of ammonia and water, which allows water to melt at a much lower temperature. This is lava on Titan, a stinky mix of water and ammonia, molten at minus 150 degrees.

You can build anything from small cones to large mountains on Titan, out of this stuff.

If you were a visitor and you walked up and you put your hand on a lava flow, you wouldn't burn your hand, you would freeze it.

In stark contrast to the cryovolcanoes and wet polar lake lands, bordering the equator are vast Titanian deserts, covered in dunes.

I think it would be one of the seven wonders of the solar system, what you would see is almost unending sea of massive dunes, exactly the same size and scale of dunes that we see on earth, some areas where you see nothing, but dunes for hundreds and hundreds of kilometers