Libra Constellation: Facts, location, stars and exoplanets of the scales

天秤座：事实，位置，恒星和系外行星

The constellation of Libra — Latin for the weighing scales — is the only constellation of the Zodiac to be named after an inanimate object rather than a character or an animal. Libra is located in the southern sky and has been a strong influence in mythology, astrology, and hard science.

天秤座--拉丁语称秤--是黄道十二宫中唯一一个以无生命物体而不是人物或动物命名的星座。天秤座位于南方天空，在神话、占星术和硬科学中有着十分强大的影响力。

For our ancestors, the constellation was long associated with harmony, balance, and even justice. Now in the modern era of science, it represents one of the most enticing targets for astronomers and plays host to some fascinating cosmic objects.

对我们的祖先来说，星座长期以来一直与和谐、平衡甚至正义联系在一起。现在在现代科学时代，它对天文学家来说是最诱人的目标之一，此外，它还是一些迷人的宇宙天体的宿主。

The constellation's exoplanets could prove to be tantalizing prospects for deeper investigation, with some even possibly hosting liquid water — a key ingredient for life.

该星座的系外行星被证明是诱人的深入研究的前景，其中一些甚至可能含有液态水--生命的关键成分。

Related: What is a 'morning star,' and what is an 'evening star'?

相关：什么是“晨星”，什么是“晚星”？

The constellation of Libra is located in the Southern Hemisphere during winter and the Northern Hemisphere in summer. It is best seen in the Northern Hemisphere in late spring/early summer with the ideal time to observe Libra being at 9 p.m. during June evenings, according to the astronomy website Planet Guide.

天秤座冬季位于南半球，夏季位于北半球。根据天文学网站行星指南，北半球最好在春末/夏初看到天秤座，观察天秤座的理想时间是6月晚上9点。

In the southern sky, it can be found at about 15 hours 30 minutes right ascension and 15° south declination according to Britannica.

在南部天空，根据大英百科全书，它可以在大约15小时30分钟的赤经和15度的南赤纬处找到。

The constellation is positioned between Scorpius on the east and Virgo on the west. Libra also borders the constellations of Serpens Caput, Hydra, Centaurus, Lupus, and Ophiuchus.

星座位于东方的天蝎座和西方的处女座之间。天秤座也与蛇头、九头蛇、半人马座、狼疮和蛇夫座的星座接壤。

Until 729 BCE the sun was in autumnal equinox in Libra, at this time precession of the equinoxes shifted the equinox to Virgo. In 2439 the autumnal equinox will shift again, this time moving to the constellation Leo.

直到公元前729年，太阳在天秤座的秋分，此时的岁差将秋分转移到处女座。在2439年秋分将再次移动，这次移动到狮子座。

The stars of Libra are fairly faint with its brightest star, Zubeneschamali or Beta Librae (β Lib) —a blue dwarf star which is located 160 light-years from Earth —  having a magnitude of 2.7. According to Burnham's Celestial Handbook Amateur astronomer Willian Tyler Olcott once said that Zubeneschamali is "… the only naked-eye star that is green in color." Most modern astronomers consider it white or blue.

天秤座的恒星相当微弱，它最亮的恒星Zubeneschamali或Beta Librae(βLib)--一颗距离地球160光年的蓝矮星--星等为2.7。根据伯纳姆的天体手册，业余天文学家威利安·泰勒·奥尔科特曾经说过，Zubeneschamali是“……唯一一颗肉眼可见的绿色恒星。”大多数现代天文学家认为它是白色或蓝色的。

β Lib, also called Lanx Australis ("the southern scale"), makes up the upper part of the scale linking the two balances, which hang from the triangle at an angle along with two of the constellation's other brightest stars.

βLib，也被称为Lanx Australis（“南方天平”），构成了连接两个天平的天平的上部，这两个天平与该星座其他两颗最亮的恒星以一个角度悬挂在三角形上。

These are the second brightest star Alpha Librae (α Lib) which despite its alpha designation, is also called Zubenelgenubi ("southern claw") — a binary star located 77 light-years from Earth — and Gamma Librae (γ Lib), an orange giant of magnitude 3.9, lying around 152 light-years from Earth, according to the astronomy website Constellation Guide. Another star of note in the constellation of Libra is the red giant star Brachium ("arm") or Sigma Librae (σ Lib).

根据天文学网站星座指南，这是第二亮的恒星Alpha Librae(αLib)，尽管它被命名为Alpha，但它也被称为Zubenelgenubi（“南爪”）--一颗距离地球77光年的双星--和伽马Librae(γLib)，一颗3.9级的橙色巨星，距离地球约152光年。天秤座中另一颗值得注意的恒星是红巨星臂（“臂”）或西格玛Librae(σLib)。

Libra is also the constellation that hosts the bright star cluster NGC 5897 located 40,000 light-years from Earth.

天秤座也是位于距地球40,000光年的明亮星团NGC5897的星座。

One of the most extraordinary stars we have yet to discover, HD 140283 or Methuselah. Located around 190 light-years from Earth, is found in Libra. This metal-poor subgiant is predominantly made of hydrogen and helium and is therefore clearly old, but when it was first discovered it appeared to be 16 billion years old, older than the age of the universe itself — 13.8 billion years.

我们迄今发现的最非凡的恒星之一，HD 140283或玛士撒拉。位于距地球190光年的天秤座。这个金属贫乏的亚巨星主要由氢和氦组成，因此显然很古老，但当它首次被发现时，它似乎有160亿年的历史，比宇宙本身的年龄--138亿年还要老。

Though early estimates of age have been reduced by further study, the star remains an enigma as it is dated at 14.46 billion years with an uncertainty of 800 million years, according to Constellation Guide. While this is more consistent with the age of the universe it is an age that still makes it one of the universe's oldest stars.

根据星座指南，尽管早期对年龄的估计已经通过进一步的研究减少了，但这颗恒星仍然是一个谜，因为它的年龄为144.6亿年，不确定性为8亿年。虽然这更符合宇宙的年龄，但这一年龄仍然使它成为宇宙中最古老的恒星之一。

As well as some fascinating stars, Libra is also home to some remarkable extrasolar planets. Foremost amongst these are the exoplanets that orbit the red dwarf Gliese 581 located 20.5 light-years from Earth.

除了一些迷人的恒星，天秤座也是一些非凡的太阳系外行星的家园。其中最重要的是围绕红矮星Gliese581运行的系外行星，距离地球20.5光年。

These include Gliese 581e with a mass around twice that of Earth, Gliese 581c with 5 times the mass of our planet, Gliese 581d with a mass 7 times that of Earth, and Gliese 581b with a mass 16 times that of our world, according to NASA Exoplanet Exploration.

根据美国宇航局的系外行星探索，这些包括质量约为地球两倍的Gliese 581E、质量为地球5倍的Gliese 581C、质量为地球7倍的Gliese 581D和质量为地球16倍的Gliese 581B。

The latter planet is also the furthest out, orbiting its star over a period of 66.8 days. Closest to its parent star is Gliese 581e with a year that lasts just 3.15 days. Both Gliese 581c and Gliese 581d are located in the habitable zone around their star — the region where it is neither too hot nor too cold for liquid water to exist, and could therefore be habitable.

后一颗行星也是最远的，围绕其恒星运行了66.8天。最接近母星的是格利泽581E，一年仅持续3.15天。Gliese 581c和Gliese 581d都位于其恒星周围的宜居带--该区域对液态水来说既不太热也不太冷，因此可以居住。

The habitable zone of this system may also possess another world — Gliese 581g — which could be a primary candidate for hosting liquid water, a key element for life. That is if it exists. The planet's existence is currently controversial at best. Also unconfirmed is Gliese 581f, hypothesized to exist at the very edge of the system, far from its host star and as a result far too cold to support life.

这个系统的宜居带也可能拥有另一个世界--格利泽581 g--它可能是液态水的主要候选宿主，液态水是生命的关键元素。如果它存在的话。这颗行星的存在目前充其量是有争议的。Gliese581f也没有得到证实，被假设存在于系统的边缘，远离它的宿主恒星，因此太冷了，无法支持生命。

Related: Alien landscapes: 15 places on Earth that look exoplanetary

相关：外星景观：地球上看起来像外行星的15个地方

Also located in Libra is the Jupiter-like exoplanet 23 Librae b which has at least twice the mass of the gas giant and could even be 34 times as massive as the solar system's largest world.

同样位于天秤座的还有类似木星的系外行星23 Librae b，它的质量至少是气体巨星的两倍，甚至可能是太阳系最大世界的34倍。

The planet orbits a yellow-orange main sequence dwarf star located around 84 light-years from Earth that has a similar mass to the sun. The exoplanet was discovered in 1999 with its mass and orbital period of 258 days better constrained in 2009, according to Constellation Guide.

这颗行星围绕着一颗黄橙色的主序矮星运行，它距离地球约84光年，质量与太阳相似。根据星座指南，这颗系外行星于1999年被发现，其质量和258天的轨道周期在2009年得到了更好的限制。

Also in 2009, astronomers found another smaller Jupiter-like world in the system and designated it 23 Librae. This planet takes 14 years to orbit its star 23 Librae.

同样在2009年，天文学家在该系统中发现了另一个更小的类木星世界，并将其命名为23 Librae。这颗行星绕其恒星23 Librae运行需要14年。

The ancient Babylonians associated Libra with scales and balance while the stars that comprise Libra were considered by the ancient Greeks to be part of Scorpius, with the shape of the scales once representing the cosmic scorpion's claws as they point downwards.

古巴比伦人将天秤座与天平和平衡联系在一起，而组成天秤座的恒星被古希腊人认为是天蝎座的一部分，天平的形状曾经代表宇宙蝎子的爪子，因为它们指向下方。

This association is still represented by the names of some of the objects in the constellation, for example, the star Zubeneschamali which was once part of Scorpius, whose name is Arabic for "northern claw."

这种联系仍然表现在星座中一些物体的名称上，例如，曾经是天蝎座一部分的Zubeneschamali星，它的阿拉伯语名字是“北爪”。

The link between these stars with scales was reintroduced by the Romans in the first century despite the Romans adopting much of Greek tradition. In Roman tradition, Libra was a favored constellation.

尽管罗马人采纳了希腊的许多传统，但在一世纪，罗马人重新引入了这些星星与鳞片之间的联系。在罗马传统中，天秤座是一个受欢迎的星座。

The Romans viewed the constellation as the scales of justice being held by the constellation Virgo — which sits next to Libra and represented a goddess to ancient civilizations. This association with justice has been carried over to two of its most visible stars, Zubenelgenubi and Zubeneschamali, which have been said to symbolize divine justice.

罗马人认为这个星座是处女座的正义天平，处女座位于天秤座旁边，代表着古代文明的女神。这种与正义的联系一直延续到它最明显的两颗星，Zubenelgenubi和Zubeneschamali，据说这两颗星象征着神圣的正义。

The scales of Libra were also associated with balance in the seasons and days and nights of equal length by our ancient ancestors.

天秤座的天平也与我们远古祖先的季节和日夜等长的平衡有关。

For fans of astrology, now a very separate non-scientific entity distinguished from astronomy, Libra is the seventh sign of the Zodiac the birth sign of people born between September 23 and October 22.

对于占星学的粉丝来说，天秤座是黄道十二宫的第七星座，是9月23日至10月22日之间出生的人的出生星座。现在天秤座是一个非常独立的非科学实体，与天文学相区别。

Want to take a good look at Libra for yourself? Learn the Sky has a YouTube video that shows you how. Explore a spiral galaxy over 150 million light-years away in the constellation of Libra with this captivating Hubble Space Telescope image of NGC 5793. Learn more about constellations and how they were named with this informative article from NASA Science.

想自己好好看看天秤座吗？学习天空有一个YouTube视频告诉你如何。用这张迷人的哈勃太空望远镜NGC5793图像探索1.5亿光年外的天秤座螺旋星系。了解更多关于星座和他们如何命名与这篇来自美国宇航局科学的信息文章。

Libra Constellation, Constellation Guide.

天秤座，星座指南。

Libra, Britannica.

天秤座，大英百科全书。

McClure. B., Is Zubeneschamali a green star? EarthSky

麦克卢尔。B、Zubeneschamali是绿色明星吗？Earthsky

Crookes. D., Methuselah: The oldest star in the universe, Space.com.

骗子。D、玛士撒拉：宇宙中最古老的恒星，space.com。

Gliese 581, NASA Exoplanet Exploration.

Gliese 581，美国宇航局系外行星探测。

Gliese 581, Open Exoplanet Catalogue.

Gliese 581，开放系外行星目录。

23 Librae, SolStation

23 SolStation Librae