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Avatar may be breaking box office records here on Earth, but another 3-D event is creating a stir beyond our solar system. Astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, have used phenomena called light echoes to reconstruct in three dimensions the explosive death of a giant star whose light originally touched our world 330 years ago. Such echoes occur when the supernova's bright flash bounces off of dust clouds in various locations around the galaxy. Like strategically placed mirrors, the reflections can convey subtle details about these titanic explosions. In the case of this star, called Cassiopeia A, the 3-D reconstruction reveals that some parts of the blast traveled nearly 15 million kilometers per hour faster than others (green areas), giving Casiopeia A's demise a rather non-spherical appearance—something that can be seen here without the aid of special glasses. |
三維電影《阿凡達(dá)》可能正在地球上創(chuàng)造票房紀(jì)錄，但是另外一個三維事件正在太陽系之外引起轟動。馬薩諸塞州劍橋市哈佛-史密森天體物理中心的天文學(xué)家們利用被稱為“回光”的現(xiàn)象，重現(xiàn)了一顆巨型恒星爆炸死亡的三維圖像。該恒星的光線是在330年前最初到達(dá)我們地球的。當(dāng)超新星明亮的閃光通過星系周圍不同之處的塵埃云團(tuán)反射回來時，回光現(xiàn)象就產(chǎn)生了。就象處于關(guān)鍵位置的鏡子，其映像可以表現(xiàn)出這些大型爆炸事件的細(xì)微之處。至于這顆被稱為“仙后座A”的恒星，三維重現(xiàn)圖像顯示沖擊波的某些部分比其他部分（綠色部分）穿行速度每小時快1,500萬公里，在很大程度上使仙后座A的殘骸呈現(xiàn)出非球形外觀，這一點在地球上不用借助于特殊的望遠(yuǎn)設(shè)備就可以看得到。 |
