Comet ISON could well be the brightest and most spectacular comet for a generation. It should appear above the eastern horizon from December 2013 as a glorious streak across the sky. ISON has been travelling towards the sun for ten thousand years and will make only one orbit through its corona before disappearing off into the outer solar system. But as well as providing a great spectacle, ISON's tail of vapourised gas and water, hundreds of millions of kilometres long, wi[ZiYuantun.Com]ll give insights into some of the greatest mysteries of science; it will help explain the origins of the solar system, whether earth's water was delivered on comets and even whether we are alone in the universe. @BBC2 译文(3): ISON彗星很可能是一代人以来最明亮、最壮观的彗{资源屯-ziyuantun.com}。从2013年12月起，它应该会出现在东方地平线上，成为一条横跨天空的光辉条纹。ISON已经向太阳运行了一万年，在消失在外太阳系之前，它只会绕一圈穿过日冕。
