60秒科学:Fog Found on Saturn's Moon Titan

Fog Found on Saturn¹'s Moon Titan
A study in Astrophysical Journal Letters reveals that Titan may be home to the familiar atmospheric² condition known as fog--but made out of methane³. Karen Hopkin reports

The northeast just had its first big snow of the season. Meanwhile, on Titan, it was foggy. That weather report brought to you by researchers publishing in the journal Astrophysical Journal Letters. The scientists found that Titan, Saturn’s largest moon, is covered with puddles⁴ of liquid methane, which give rise to a fog that’s as thick as pea soup—and smells a whole lot worse.

To make fog, you need lots of liquid. Here on earth, we use water. We’ve got water on the ground and in the air. And when the air can’t hold any more moisture because it’s totally saturated⁵ or it cools down, you get condensation⁶. So the morning fog, and the dew on your windshield, comes from air that’s cooled enough that it can’t hang onto its water.

Titan fog, on the other hand, comes from methane. Like water, methane can be a solid, liquid, or gas. On Titan, methane forms clouds and maybe even rain. And, when atmospheric methane condenses, it makes fog. That fog then sticks around because it’s in contact with the methane puddles, which keeps everything cool enough to keep the methane condensing.

So next time you visit Titan, don’t expect to get any great pictures of Saturn. And drive with your low beams on.
 

1 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

2 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

3 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

4 puddles   

n.水坑， （尤指道路上的）雨水坑( puddle的名词复数 )

参考例句：

• The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。
• The road was filled with puddles from the rain. 雨后路面到处是一坑坑的积水。 来自《简明英汉词典》

5 saturated   

a.饱和的，充满的

参考例句：

• The continuous rain had saturated the soil. 连绵不断的雨把土地淋了个透。
• a saturated solution of sodium chloride 氯化钠饱和溶液

6 condensation   

n.压缩，浓缩；凝结的水珠

参考例句：

• A cloud is a condensation of water vapour in the atmosphere.云是由大气中的水蒸气凝结成的。
• He used his sleeve to wipe the condensation off the glass.他用袖子擦掉玻璃上凝结的水珠。