加利福尼亚两家技术研究院研究人员最近出版了头条新闻文章in the Astronomical Journal, announcing that they'd found evidence of a giant planet on the edge of our solar system, moving in a strange, elongated orbit as far as930亿英里(150 billion kilometers) from the sun.
新发现的世界，他们绰号为九个星球，似乎比冥王星远远15倍，是剥夺了其全尺寸星球地位和的矮人行星的巨大约5,000倍。demoted2006年国际天文联盟。
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“这将是一个真正的第九星球，”加州理工学院的行星天文学教授迈克·布朗（Mike Brown）与同事康斯坦丁·巴蒂金（Konstantin Batygin）一起找到了地球的证据。新闻稿。Unlike Pluto, Planet Nine could be so massive that its gravity dominates a region of the solar system that's bigger than any of the other known planets — something that Brown said makes it “the most planet-y of the planets in the whole solar system.”
But those who aren't space scientists may be a little puzzled. If Planet Nine is so gosh-darned humongous, then how come it took so long for somebody to realize it was out there? And why hasn't anybody actually seen it? (Brown and Batygin figured out that it probably exists by using mathematical modeling and computer simulations, not direct observation.)
But when we think things like that, we're only revealing how little we know about the immense scale of our solar system, and the challenge of perusing that vast expanse. If anything, what's really remarkable is that someone could discover Planet Nine at all. Doing that required not just ingenuity but a series of prior discoveries and false starts that eventually provided clues about the probable existence of the giant world.
使布朗和巴蒂金的发现更加引人注目的一件事是，九行星可能是自1846年以来发现的第一个真正的星球（对不起，冥王星）。海王星首次。He knew where to look because two other scientists, John Couch Adams of Britain and Frenchman Urbain Jean Joseph Le Verrier, had noticed that the planet Uranus was being pulled slightly out of its normal orbit, and calculated that the effect was being caused by yet another unknown planet.
天文学家经常采取这种推论以进行发现，因为在广阔的空间中观察行星大小的物体仍然非常非常困难。当他们能够检测到extrasolar planets, for example, it's usually by检测他们对恒星轨道的影响。
Though Planet Nine appears closer than those worlds, it's still hundreds of times as far away from the sun as our planet. It's so far away that the sunlight that falls on it would be about 300,000 times weaker than the light that reaches us, as SETI Institute senior astronomerSeth Shostak已经写过了。An object that's so far away and reflecting so little light at a telescope would be dauntingly difficult to spot, even if you knew pretty much where to look.
“它太远了，它非常微弱！”布朗在电子邮件中解释了。
正如布朗所详述博客文章160年来，天文学家一直在太阳系边缘寻找另一个星球。他们大部分时间都花了很多时间研究已知行星的线索的位置，尽管这是由于1993年的分析证明它们正是应有的位置，但事实证明这是一个死胡同。
But astronomers' discovery in the early 1990s of the Kuiper Belt, a region filled with thousands of small objects, provided new clues. In March 2014, a Nature文章天文学家乍得·特鲁吉洛（Chad Trujillo）和斯科特·谢泼德（Scott Sheppard）指出，一些最遥远的柯伊伯带物体具有异常的轨道对准，并建议该效应是由一个小星球的重力造成的。根据布朗的说法，该想法最终被计算机模拟所证实，但那个9月，巴西和日本天文学家提出，一套不同的Kuiper带对象受到未发现的星球的重力的影响。
When Brown and Batygin pondered the other scientists' findings, they began seeing a new possibility. According to a Caltech press release, they eventually realized that the six most distant objects in Trujillo's and Sheppard's study all followed elliptical orbits that pointed in the same direction in space, which was difficult to explain, because the objects were traveling in orbit at different rates. They ran numerous computer simulations to test various possible explanations. “The computers have gotten ever more powerful, so we can do more simulations faster than ever,” Brown explained in his email.
最终，两人看到，如果他们使用假设的巨大行星进行模拟，则在所谓的反对准轨道上进行了模拟 - 该行星的围栏或最接近太阳的路径是来自所有其他物体的180度，已知太阳系中的行星 - 他们六个奇怪的行为对象在他们实际上实际上所做的奇怪对准中移动了。
但是，尽管布朗和巴蒂金已经弄清了第九行星的粗糙轨道，但他们不知道地球的精确位置。因此，有人在望远镜中观察它可能需要一段时间。布朗说，虽然他希望成为第一个发现它的人，但他还希望其他天文学家会受到启发参加搜索。
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