英语听力：自然百科 金星和水星旅行指南 Venus and Mercury-4

 Many aspects, like its geological past, are a mystery. But some things we do know, this lonely planet has a strange sense of keeping time. Once you arrive, you have to reset¹ your watch for a time zone like no other.

 

It has such an unusual orbit and rotation² period, the days and nights are, are very strange. A Mercurian year is just 88 earth days long, thanks to its quick sprint³ around the sun. But it rotates so slowly, a single day takes much longer.

 

The day on Mercury is more like half a year, eh, earth terms.

 

Although known to us since ancient times, for thousands of years we had little idea what the planet really looked like. Then in 1974, NASA's Mariner⁴ 10 sends back the first ever glimpses of its surface.

 

Pictures can be transmitted to tracking stations and on to the Jet Propulsion Laboratory in California.

 

Due to Mercury's slow\ rotation and its elliptic orbit around the sun, when it flew by three times, it saw the same half of the planet. So we've really only seen something like 45% of the planet at relatively⁵ low resolution.

 

 

Hidden in these fuzzy black and white postcards for over 30 years are clues that point to one of Mercury's biggest puzzles. It's been shrinking. Mercury doesn't have plate tectonics like the earth does. So we know that Mercury's crust is under a lot of compression. The only way it can really do that is if the planet shrank. And so you can think of it as the incredible, shrinking planet.

 

 

As Mariner 10 flies past, the mystery deepens. The spacecraft detects a vast iron core hidden inside

1 reset   

v.重新安排，复位；n.重新放置；重放之物

参考例句：

• As soon as you arrive at your destination,step out of the aircraft and reset your wristwatch.你一到达目的地，就走出飞机并重新设置手表时间。
• He is recovering from an operation to reset his arm.他做了一个手臂复位手术，正在恢复。

2 rotation   

n.旋转；循环，轮流

参考例句：

• Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
• The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。

3 sprint   

n.短距离赛跑；vi. 奋力而跑，冲刺；vt.全速跑过

参考例句：

• He put on a sprint to catch the bus.他全速奔跑以赶上公共汽车。
• The runner seemed to be rallied for a final sprint.这名赛跑者似乎在振作精神作最后的冲刺。

4 mariner   

n.水手号不载人航天探测器，海员，航海者

参考例句：

• A smooth sea never made a skillful mariner.平静的大海决不能造就熟练的水手。
• A mariner must have his eye upon rocks and sands as well as upon the North Star.海员不仅要盯着北极星，还要注意暗礁和险滩。

5 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。