向太阳系外第一颗已知的彗星问好

向太阳系外第一颗已知的彗星问好

Our solar system is getting another visitor from a faraway galaxy.

我们的太阳系迎来了另一位来自遥远星系的访客。

2I/Borisov was known as C/2019 Q4 before it became official. (Photo: Gemini Observatory/NSF/AURA)

An amateur astronomer from Crimea named Gennady Borisov first spotted the fast-moving fleck in the night sky last month. Since then, both Hawaii's Gemini Observatory and Spain's William Herschel Telescope have confirmed a trajectory that could take it within 190 million miles of our sun.

一位来自克里米亚的业余天文学家Gennady Borisov上个月首次在夜空中发现了这个快速移动的斑点。从那以后，夏威夷的双子座天文台和西班牙的威廉·赫歇尔望远镜都证实了这条轨道可以把它带到离太阳1.9亿英里以内的地方。

The Gemini Observatory even managed to snap a startling full-color picture of the celestial body as it streaked through the heavens.

双子座天文台甚至成功地拍下了一幅令人吃惊的天体在天空中划过时的全彩照片。

And, judging by its woolly white halo and telltale tail, it looks like we're entertaining our first interstellar comet.

而且，从它毛茸茸的白色光环和能说明问题的尾巴判断，它看起来像是在款待我们的第一颗星际彗星。

Publishing their findings this month in the journal ArXiv, the Polish researchers who analyzed the data have dubbed the visitor C/2019 Q4 (Borisov).

本月，波兰研究人员在《ArXiv》杂志上发表了他们的研究成果，他们分析了这些数据，并将其命名为游客C/2019 Q4 (Borisov)。

"Both orbital and morphological properties of this body show that this is the first certain case of an interstellar comet," the authors note in the study.

“这个天体的轨道和形态特征都表明，这是第一颗星际彗星，”作者在研究中指出。

Scientists at the International Astronomers Union (IAU) concurred with their findings, designating it the second interstellar object — meaning Borisov has now been crowned 2I/Borisov to honor that status.

国际天文学家联盟(IAU)的科学家们同意他们的发现，将它命名为第二个星际物体——这意味着波里索夫现在被命名为2I/波里索夫以纪念这一地位。

"The orbit is now sufficiently well known, and the object is unambiguously interstellar in origin," according to a release by the IAU.

国际天文学联合会发布的一份新闻稿称:“这颗行星的轨道现在已经足够为人所知，而且它的起源也很明确，是星际间的。”

From another world

从另一个世界

It's only the second time we've detected an interstellar object. The comets that typically blaze through our neighborhood hail from within the solar system — either from that icy outermost region known as the Oort Cloud or the Kuiper Belt, a veritable comet factory just beyond Neptune's orbit.

这是我们第二次探测到星际物体。通常在我们周围燃烧的彗星来自太阳系内部——要么来自被称为奥尔特云(Oort Cloud)的最外层结冰区域，要么来自柯伊伯带(Kuiper Belt)，这是海王星轨道之外一个名副其实的彗星工厂。

And while some of these celestial objects don't come around here very often — Comet West, for example, has an orbital period of about 250,000 years — they all call our solar neighborhood home. In all, there are likely more than 6,000 comets sailing around our space, all eventually brought to heel by our sun's gravitational leash.

虽然这些天体中有一些并不经常出现在这里——例如，慧星韦斯特的轨道周期约为25万年——但它们都把我们的太阳邻居称为家。总之，可能有超过6000颗彗星在我们的太空中航行，最终都被太阳的引力牵引着。

But 2I/Borisov has made the longest journey of all. Researchers say it won't loop around our sun, like its domestic counterparts. It's also traveling at a torrid 93,000 miles per hour — a speed that's far faster than any of the local spaceballs could muster. At that pace, not even the sun will be able to reel it in.

但是2I/Borisov的旅程却是最长的。研究人员表示，它不会像国内的太阳那样环绕太阳运行。它还以每小时93000英里的惊人速度飞行——这一速度远远超过了当地任何一个太空球的速度。以这样的速度，连太阳都无法把它卷进去。

Artist's impression of the first known interstellar asteroid, 'Oumuamua. (Photo: M. Kornmesser/ESO)

Strangely enough, this is the second time we've had an interstellar visitor in as many years. In 2017, a very strange object known as 'Oumuamua graced our solar system. Its unwieldy, cigar-like dimensions, unknown origin point and blazing speed sparked a frenzy of scientific speculation. While some scientists suggested it's a hobbled, tail-less comet that has been wandering the galaxy for billions of years, others just came right out and said what many of us were thinking: alien spaceship.

奇怪的是，这是这么多年来我们第二次迎来星际访客。2017年，一个名为“Oumuamua”的非常奇怪的天体出现在我们的太阳系中。它笨重的雪茄状外形、未知的起源点和惊人的速度引发了一场疯狂的科学猜测。虽然一些科学家认为这是一颗步履蹒跚、没有尾巴的彗星，已经在银河系中游荡了数十亿年，但另一些科学家却直截了当地说出了我们许多人的想法:外星人的宇宙飞船。

2I/Borisov is a little less ambiguous. Even though it was born in an incomprehensibly foreign space, it bears all the telltale trappings of comethood — specifically a lustrous tail of glitter likely caused by outgassing from its ice-cold heart.

2I/Borisov就不那么模棱两可了。尽管它出生在一个难以理解的陌生空间，但它身上却有着所有能说明问题的喜剧特征——特别是一条闪闪发亮的尾巴，很可能是由它冰冷的心脏释放出的气体造成的。

In any case, we'll get a chance to scrutinize 2I/Borisov a lot more closely as it brightens our doorstep over the coming weeks. While 'Oumuamua didn't stick around long enough for us to unfurl the "Welcome to Earth" banner, Borisov should make its nearest pass to Earth in December. It won't be quite as intimate as 'Oumuamua's visit, which scraped within 180 million miles of Earth. But it will light up the night sky a lot longer. The flyby will be closest to Earth on Dec. 8 — when the comet will be 190 million miles away — but will be present through April, when it finally bids our solar system a fond farewell.

无论如何，我们将有机会更仔细地观察2I/Borisov，因为它将在未来几周照亮我们的大门。虽然Oumuamua没有停留足够长的时间让我们展开“欢迎来到地球”的横幅，但是Borisov应该在12月到达最近的地球。这次访问不会像“Oumuamua的访问”那么亲密，“Oumuamua的访问”距离地球不到1.8亿英里。但它将照亮夜空更长的时间。这次飞越将在12月8日离地球最近——届时彗星将在1.9亿英里之外——但将持续到4月，届时它将与我们的太阳系告别。