萬(wàn)物簡(jiǎn)史 第33期:埃文斯牧師的宇宙(2)

Surprisingly little of the universe is visible to uswhen we incline our heads to the sky. Only about6,000 stars are visible to the naked eye from Earth,and only about 2,000 can be seen from any one spot.With binoculars the number of stars you can seefrom a single location rises to about 50,000, and witha small two-inch telescope it leaps to 300,000.

令人吃驚的是，當(dāng)我們把腦袋探向天空的時(shí)候，我們只能看見(jiàn)宇宙的極小部分。從地球上，肉眼只能見(jiàn)到大約6 000顆恒星，從一個(gè)角度只能見(jiàn)到大約2000顆。如果用了望遠(yuǎn)鏡，我們從一處看見(jiàn)的星星就可以增加到大約5000顆;要是用一臺(tái)5厘米的小型天文望遠(yuǎn)鏡，這個(gè)數(shù)字便猛增到30萬(wàn)顆。

With a sixteen-inch telescope, such as Evans uses, you begin to count not in stars but ingalaxies. From his deck, Evans supposes he can see between 50,000 and 100,000 galaxies, eachcontaining tens of billions of stars. These are of course respectable numbers, but even with somuch to take in, supernovae are extremely rare.

假如使用像埃文斯使用的那種40厘米天文望遠(yuǎn)鏡，我們就不僅可以數(shù)恒星，而且可以數(shù)星系。埃文斯估計(jì)，他從陽(yáng)臺(tái)上可以看到的星系可達(dá)5萬(wàn)-10萬(wàn)個(gè)，每個(gè)星系都由幾百億顆恒星組成。這當(dāng)然是個(gè)可觀的數(shù)字，但即使能看到這么多，超新星也是極其少見(jiàn)的。

A star can burn for billions of years, but it dies just once and quickly, and only a few dying starsexplode. Most expire quietly, like a campfire at dawn. In a typical galaxy, consisting of ahundred billion stars, a supernova will occur on average once every two or three hundredyears.

一顆恒星可以燃燒幾十億年，而死亡卻是一下子的事兒。只有少量的臨終恒星發(fā)生爆炸，大多數(shù)默默地熄滅，就像黎明時(shí)的篝火那樣。在一個(gè)由幾千億顆恒星組成的典型星系里，平均每二三百年會(huì)出現(xiàn)一顆超新星。

Finding a supernova therefore was a little bit like standing on the observation platform ofthe Empire State Building with a telescope and searching windows around Manhattan in thehope of finding, let us say, someone lighting a twenty-first-birthday cake.

因此，尋找一顆超新星，有點(diǎn)像立在紐約帝國(guó)大廈的觀景臺(tái)上，用望遠(yuǎn)鏡搜索窗戶(hù)外的曼哈頓四周，希望發(fā)現(xiàn)--比如說(shuō)--有人在點(diǎn)著21歲生日蛋糕上的蠟燭。