時差N小時:灶神星
在晴朗的夜空下我們能夠看到木星，那是因為木星夠大;
Mars and Mercury are smaller than that, and youcan see them, too.
盡管火星和水星比木星要小，但我們依然能看到。
Wait a minute, our moon is even smaller,and you can see that.
等等，月球更要小一些，我們還是能看到。
Could anything smaller than the moon be visible without a telescope?
那么，在不使用望遠鏡的情況下，我們還能看到比月亮更小的天體嗎?
Actually, yes.
事實上，答案是肯定的。
Though it takes a lot of patience and excellent sky conditions, it is possible to see atiny object called Vesta.
只要我們足夠有耐心，天公也作美，我們還有機會看到一個小天體—它就是被命名為灶神星的小天體。
Although it had a molten interior and volcanoes, Vesta isn't a planet or amoon: it's an asteroid.
盡管它以溶化的金屬為核心且地表遍布火山，灶神星卻既不是行星也不是月球：它僅僅是一顆小行星。
Asteroids are straychunks of rocky or metallic materials that orbit thesun but were never drawn into any of the planets.
小行星是由巖石或是金屬塊構成的小天體，他們繞太陽運動但絕不會卷入其他行星的運行軌道中。
Vesta is quite far away.
灶神星距地球的距離很遠。
Like many asteroids, it has an orbit out between the orbits of Mars and Jupiter.
像其它許多小行星一樣，它在火星與木星之間有自己的運行軌道。
Astronomers first spotted it when looking for a new planet they thought should existbetween these two.
天文學家們首次發(fā)現它時是在尋找介于這兩大行星間的另一個行星。
As I said, Vesta is quite small-about three hundred and twenty-five miles across.
正如我所說，灶神星是很小的—它的直徑也就只有325英里而已。
So if it's small and far away, how come we can see it from here?
那問題就是，它又小，距離我們又遠，我們怎么能從地球上靠肉眼就看到它呢?
Vesta's surface has a coating of pyroxine and olivine,two minerals that are actually also spewed up by volcanoes here on earth.
在灶神星的表面覆蓋了厚厚的一層玄武巖和橄欖石，這兩種礦物質都是由此處的火上噴發(fā)而出的。
They give it a whitishexterior that reflects well,
這兩種礦物質使得灶神星的表面呈白色，且發(fā)光的效果相當好。
making it just possible to see Vesta with your eyes, even when the onlytwo larger asteroids, Ceres and Pallas, are completely invisible.
如此一來，我們便僅憑肉眼就可以看到灶神星了。甚至在比它還大的另外兩個小行星—谷神星和智神星都無法看到的情況下，我們還是能看到它。
