By Jonathan Amos, BBC News

媒體英語會帶大家一起學習BBC撰稿人在報道世界大事時常用到的單詞和短語。

Background:土衛六是土星最大的衛星，它主要是由水、冰和山脈組成。科學家近日在舊金山召開的美國地球物理學聯合會上宣稱他們可能在土衛六上發現了冰火山。

Titan shroudedis a mysterious world. Because it's shrouded in a thick, oily haze, it's extremely hard to identify anything at the moon with confidence. But with temperatures that plunge to minus 180 Celsius at the surface, researchers had suspected it might have ice volcanoes.

And now the Cassini probe has spotted a 1,500m-high mountain with a deep pit in it, and what looks like a flow of material nearby.

Scientists can only speculate what sort of material a cryo-volcano might erupt, but the complex chemistry at Titan suggests it could be a slushy water-ice containing ammonia.

If there are a lot of carbon molecules present, the lava could even look like softened asphalt, candle wax or even polyethylene.

The team which discovered the mountain have dubbed it "The Rose".