英語(yǔ)聽(tīng)力文摘492 塞德娜

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Sedna 塞德娜

(本文寫(xiě)于2004年)

Pluto is the last of the nine planets, and when it’s at its farthest point in its elliptical orbit, it’s the farthest planet from the sun. That's true, but incorrect. Well, what you said about Pluto is true, but you left out super-distant object is only found recently, such as Sedna. Sedna?

Sedna’s been dubbed a “planetoid”–think of it as a mini-planet, three quarters as big as Pluto. It’s smaller than our moon. But Sedna may have a moon of its own, and if it were a lot closer, we might have called it a planet long ago.

Sadly for Sedna, though, it’s way out there–about eight billion miles away. Eight billion? That’s a whopping three times farther from the sun than even Pluto is. Sedna is so distant, and tiny, that it was only discovered for the first time this year by astronomers at the California Institute of Technology in Pasadena.

Sedna is already fascinating folks, though, because it is very reflective and reddish colored, confusing astronomers as to what it might be made of. It also has a bizarrely elongated orbit, going around the sun only once every ten thousand years!

冥王星是九大行星中最后被發(fā)現(xiàn)的一顆。它處在橢圓軌道的最遠(yuǎn)點(diǎn)，同時(shí)也是離太陽(yáng)最遠(yuǎn)的行星。那是事實(shí)，但不準(zhǔn)確。關(guān)于冥王星你所說(shuō)的是對(duì)的，但是你忽視了超遠(yuǎn)距離的物體是最近才發(fā)現(xiàn)的，比如塞德娜。塞德娜?

塞德娜被稱(chēng)為“小行星”，其體積大小為冥王星的四分之三，比月球小一點(diǎn)。但是塞德娜也許有其自己的衛(wèi)星，而且如果它能離得更近，我們也許很久以前就稱(chēng)其為行星了。

然而遺憾的是，它離得很遠(yuǎn)，約有80億英里遠(yuǎn)。80億英里?那它與太陽(yáng)的距離是冥王星與太陽(yáng)距離的三倍遠(yuǎn)啊。由于塞德娜那么遠(yuǎn)又那么小，因此帕薩迪納市加州理工學(xué)院的天文學(xué)家們于今年第一次發(fā)現(xiàn)它。

然而，塞德娜已經(jīng)讓很多人著迷了，因?yàn)樗芊瓷涮?yáng)光呈微紅色，使得天文學(xué)家們困惑它到底是由什么組成的。它還擁有奇怪細(xì)長(zhǎng)的軌道，圍繞太陽(yáng)運(yùn)行一周需要1萬(wàn)年。