英语听力：自然百科 穿越银河系的旅行 Through Milky Way—5（在线收听） |
We are taking a ride through the Milky Way. First, we are traveling to a place where stars are born. Even at the speed of light, 196,000 miles a second, the journey lasts for 1,500 years. We've arrived at the vast glowing cloud of gas and dust, the great Orion Nebula. With the Earth in this new neighborhood, the skies become a brilliantly illuminated cosmic canvas. But this cloud is more than just a work of art. It holds the key to how our sun and every star in the galaxy came to be. The first clues come from looking at the Milky Way from our perspective. It seems there is more here than just stars. With the naked eye, we can pick out large dark patches. Astronomers like James Bullock provide a clear picture. “Perhaps, the most beautiful part of this image is that we have this contrast of dark and light regions running through the plain of the disc. What that really is? It’s dust. They are clouds of dust that are casting a shadow from the back of the stars and the stars are trying to shine their light through. They are dust clouds there that blocking a light, much like a cloud on Earth would block the sun.”
These vast clouds of cosmic gas and dust stretch thousands of light-years across the Milky Way. Hubble has spotted them in most spiral galaxies. Dark, ghostly bands, woven throughout their spiral arms and spreading across their entire discs.
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| 原文地址：http://www.tingroom.com/lesson/zrbaike/2011/260145.html |