英语听力：自然百科 穿越银河系的旅行 Through Milky Way—4（在线收听） |
By comparing the detailed images, Hubble has taken another spiral galaxy. With the best images of our own taken from the ground, and by using satellites to measure the distance and density of stars in different directions, astronomers have been able to draw a grand plan of our star city. At its heart is a bright central region. This is the galactic core. From here, two majestic spiral arms, bright bands of billions of stars sweep outwards. They're called Scutum-Centaurus and the Perseus Arm. There are three smaller rounds containing smaller stars.
From one side to the other, our galaxy measures a staggering 600,000 trillion miles.
“It takes light 100,000 years to cross our galaxy. This is a big galaxy and it's quite amazing if you think about it that we understand as much as we do about the system.”
So now, we know where we are. Our sun and solar system are located here in a quiet neighborhood nestled between two spiral arms.
So we will begin our journey by taking the Earth to one of the most spectacular locations in the Milky Way, a place that holds the clue to how the two hundred billion stars in our galaxy including our own sun were first created and it's just around the corner
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| 原文地址：http://www.tingroom.com/lesson/zrbaike/2011/260144.html |