英语听力:自然百科 行星旅行:土星 Saturn—7(在线收听) |
And the icy grains on the Saturnian beaches are washed by passing traffic. When a moon comes by, it creates a wake just like a motor boat creates a wake that goes behind it. And I kind of imagine the ring particles doing an intricate cosmic dance around the planet, and I can almost picture like little ballet dancers that each with their own orbits and paths, and sometimes colliding and encountering, and sometimes not. Deeper secrets of this cosmic ballet are revealed, courtesy of a seasonal trick of the light. Once every 15 earth years, as Saturn makes its slow trip around the sun, summer swops hemispheres. In 2009, Cassini was in a perfect position to witness equinox on Saturn.
The sun at exact equinox will be shining exactly adjoining to the rings, but a little bit before / a little bit after, the sun will be low to the rings, just like the sun is now low/ from London. And invertible protuberances either up or down below the rings will pass very long shadows, and we have in fact found that the rings aren’t completely flat, there are places where the ring particles in fact form these structures that soar a mile or 2 or 3, above the planet rings. The first time in 400 years, we now know that the rings are 3 dimensional.
Enormous and enormously complicated, the rings also form a major part of Saturn’s amazing weather machine. Upon arrival you might be slightly disappointed that the cloudy face of Saturn looks a little plain. But the planet beneath the rings is wild at heart. |
原文地址:http://www.tingroom.com/lesson/zrbaike/2012/260597.html |