英语听力：自然百科 金星和水星旅行指南 Venus and Mercury-6（在线收听） |
After Messenger's 3 fly-bys, we've now mapped more than 90% of the planet. Taken from around 124 miles, these images are the clearest to date of Mercury. And it's not hard to spot a crater of epic proportions, the result of yet another Titanic collision. That's the Caloris basin, this impact basin. It covers almost 3 million square kilometers. It's one of the biggest in the solar system.
The size of / Alaska and California combined, whatever created Caloris almost destroyed the planet.
'It was like something that hangs in the water of a hundred kilometers in size. It could have been a huge comet or been a very large asteroid. It had a catastrophic effect on the surface.
Shockwaves rippled around the crust, buckling it on the opposite side. And near the center of the crater is another spectacular geological puzzle that has experts scratching their heads.
The spider is this really strange feature that is in almost the center of the Caloris basin.''
Oh, the spider, that really annoys me hearing people call it as it doesn't look like a spider. How many legs spider have? Eight, right?
It looks kind of like a hundred-legged spider/, but it has all of these radiating cracks coming out of it.
Whether the spider is the result of planetary stretch marks, or some obscure cratering process? No one knows.
It is a fascinating feature, we don't know how it formed. It’s very canalized.
So for a planet that appears inactive, more has been going on deep inside Mercury than we ever gave it credit for.
There's even more occurring above the surface that can't be seen and it involves the relentless force of the sun. |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2012/260551.html |