地球有史以來第二位星際訪客要來了

我們有史以來第二位星際訪客現(xiàn)在有了一個(gè)名字：2i/鮑里索夫

An interstellar comet on its way to visit us has been officially named after the amateur astronomer who discovered it.

一顆即將造訪我們的星際彗星以發(fā)現(xiàn)它的業(yè)余天文學(xué)家的名字正式命名。

2I/Borisov was previously known as C/2019 Q4 Borisov. The 'I' stands for 'interstellar' and the '2' because it's only the second ever seen, behind 2017's 1I/'Oumuamua.

2I/Borisov以前被稱為C/2019 Q4 Borisov。“I”代表“星際”，“2”代表這是繼2017年的“1I/ Oumuamua”之后第二次被看到。

Its recognition as an interstellar object is no surprise, with its distant origins obvious within days after Ukrainian skywatcher Gennady Borisov saw it in August on his home-made telescope.

它被確認(rèn)為一顆星際物體并不令人意外，在烏克蘭天文觀測(cè)者根納季·鮑里索夫(Gennady Borisov)今年8月用自制望遠(yuǎn)鏡觀測(cè)到它幾天后，它的遙遠(yuǎn)起源就顯而易見了。

"After a week of observations by amateur and professional astronomers all over the world, the Minor Planet Center was able to compute a preliminary orbit, which suggested this object was interstellar," the International Astronomical Union said.

國(guó)際天文聯(lián)合會(huì)說：“經(jīng)過全世界業(yè)余和專業(yè)天文學(xué)家一周的觀測(cè)，小行星中心能夠計(jì)算出一個(gè)初步軌道，這表明這個(gè)天體是星際天體。”

"The orbit is now sufficiently well-known, and the object is unambiguously interstellar in origin; it has received its final designation as the second interstellar object, 2I. In this case, the IAU has decided to follow the tradition of naming cometary objects after their discoverers, so the object has been named 2I/Borisov."

“現(xiàn)在，這個(gè)軌道已經(jīng)足夠?yàn)槿怂?，而這個(gè)物體的起源也很明確，是星際的;它最終被指定為第二個(gè)星際物體，2I。在這種情況下，國(guó)際天文學(xué)聯(lián)合會(huì)決定遵循以發(fā)現(xiàn)者的名字命名彗星物體的傳統(tǒng)，所以這個(gè)物體被命名為2I/Borisov。”

Its orbit is hyperbolic, meaning it has enough speed to escape the sun's gravitational pull. Its origins are unknown, but a paper by Polish astronomers suggests it may have been flung at us by a binary star, Kruger 60, 13 light-years away.

它的軌道是雙曲線，這意味著它有足夠的速度逃脫太陽的引力。它的起源尚不清楚，但波蘭天文學(xué)家的一篇論文表明，它可能是由13光年外的克魯格60雙星向我們拋出的。

"When searching for a home system of an interstellar body one should look for a past close proximity at a very small relative velocity of order of just a few kilometres per second," they wrote.

他們寫道:“在尋找星際體的家園系統(tǒng)時(shí)，我們應(yīng)該尋找過去非常接近的天體，其相對(duì)速度非常小，只有每秒幾公里。”

"We found that a double-star Kruger 60 is a good candidate for a home system of this comet."

“我們發(fā)現(xiàn)雙星克魯格60是這顆彗星家庭系統(tǒng)的一個(gè)很好的候選者。”

Unlike 'Oumuamua, which was only seen on its way out, Borisov is yet to arrive. It'll make its closest approach to the sun on December 7, about twice the distance from Earth to the sun.

與“Oumuamua”不同的是，鮑里索夫還沒有抵達(dá)。它將在12月7日最接近太陽，大約是地球到太陽距離的兩倍。

It'll be easiest to spot from Earth in December and January, but only from the southern hemisphere, according to space.com. It's not known whether it'll be visible to the naked eye, but is already starting to form a tail.

據(jù)space.com網(wǎng)站稱，在12月和1月從地球上最容易觀測(cè)到它，但僅限于南半球。目前還不知道它是否能用肉眼看到，但它已經(jīng)開始形成尾巴。

Its size is estimated at a few kilometres across, and its speed at 150,000km/h.

據(jù)估計(jì)，它的直徑只有幾公里，速度為每小時(shí)15萬公里。