Jupiter, Saturn Come Together in Night Sky
木星和土星在夜空中交会
The planets Jupiter and Saturn have been moving closer and closer to each other in the night sky. In fact, on December 21, they appear closer together than they have in hundreds of years.
在夜空中，木星和土星的距离越来越近。事实上，在12月21日这一天，二者之间这么近的距离，可谓是数百年难遇。
When two astronomical bodies appear close in the sky, as seen from Earth, it is called a conjunction. Conjunctions can happen with any two bodies, such as planets, moons, stars and asteroids. When Jupiter and Saturn come together, it is called a "Great Conjunction."
这两个天体在天空中靠近时，从地球上看就好像在交会。任何两个天体，如行星、卫星、恒星和小行星，都可能发生交会。木星和土星的交会被称为“大合相”。
Astronomers say these events between the two largest planets in our solar system are not especially rare. Jupiter passes its neighbor Saturn once every 20 years as they circle around the sun.
天文学家表示，作为太阳系中最大的两颗行星，二者的交会并不罕见。木星每20年就会经过其邻居土星一次，因为二者都围绕太阳运转。
But this conjunction is especially close: From Earth, the two planets will look to be just one-tenth of a degree apart. That is about the distance of one-fifth of a full moon.
但这种交会尤为接近：从地球上看，这两颗行星似乎相距仅十分之一度。这一距离约为满月直径的五分之一。
If weather permits, they should be easy to see just after sundown. This just-in-time-for-Christmas sight promises to be one of the greatest of Great Conjunctions.
如果天气允许，日落后应该很容易看到二者交会的画面。这次交会正好赶上圣诞节，因此将成为最伟大的“大合相”之一。
David Weintraub is an astronomy professor at Vanderbilt University. He told The Associated Press that a close conjunction that happens in our nighttime sky is very rare.
大卫·温特劳布是范德比尔特大学的天文学教授。他对美联社表示，在我们的夜空中发生近距离交会是非常罕见的现象。
"I think it's fair to say" that such an event usually may happen "just once in any one person's lifetime," he said. "And I think 'once in my lifetime' is a pretty good test" of whether something should be considered rare or special.
他说，“我认为可以公平地说，这类事件在任何人的一生中可能都只会发生一次。我认为‘一生中只有一次’是对某件事是否应被视为罕见或特殊的绝佳检验”。
The Jupiter-Saturn conjunction has not been this close since July 1623. But, back then, the positioning was almost impossible to see because of its closeness to the sun.
自1623年7月以来，木星与土星的交会从未如此接近过。但当时，因为距离太阳过近，所以几乎无法看到交会位置。
What makes this modern "Great Conjunction" special is it is happening at nighttime. The last time that happened was almost 800 years ago. The year was March 1226. Around that time, warrior-ruler Genghis Khan was conquering Asia.
这次现代“大合相”之所以特别，是因为其发生在夜间。上一次交会发生在800年前。时间是1226年3月。那段时间，勇士兼统治者成吉思汗正在征服亚洲。
Saturn and Jupiter have been getting closer in the south-southwest sky for weeks. Jupiter, which is bigger and closer to Earth, is much brighter.
几周来，土星和木星在西南偏南的天空中不断接近。木星更大，更接近地球，也更明亮。
"I love watching them come closer and closer to each other," said Nahum Arav in an email. He is an astronomer at Virginia Tech University. He said he loves the fact that he will see with his own eyes from his own home.
纳胡姆·阿拉夫在电子邮件中表示：“我喜欢看着它们越来越接近。”他是弗吉尼亚理工大学的天文学家。他说自已喜欢在家里用肉眼观看的感觉。
The two planets might look like one body if viewed with eyes alone. If sky watchers use binoculars they should be able to see the planets as separate. Saturn will be the smaller, less-bright body at Jupiter's upper right.
如果只用肉眼看，这两颗行星可能看起来像一个天体。如果天文观测者使用双筒望远镜，他们应该能够看到两颗行星是分开的。木星右上角那个较小且不太明亮的天体就是土星。
Even though they appear close, more than 730 million kilometers of space lies between them. Observers using telescopes will not only capture Jupiter and Saturn in the same field of view, but also some of their brightest moons.
Their next close pairing will happen March 15, 2080.
尽管二者看起来很近，但它们之间有超过7.3亿公里的距离。使用望远镜的观测者不仅能在同一视野中捕捉到木星和土星，还能捕捉到它们最明亮的卫星。二者的下一次交会将发生在2080年3月15日。
I'm Alice Bryant.
爱丽丝·布莱恩特报道。
来源：可可英语
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