译言网关于这颗Tres-2b黑暗行星的资料：
很难想象一个行星比煤炭还要黑，但是宇航员们的确声称，他们通过NASA的开普勒太空望远镜在我们所处的银河系发现了这样一颗行星。
Orbiting only about three million miles out from its star, the Jupiter-size gas giant planet, dubbed TrES-2b, is heated to 1,800 degrees Fahrenheit (980 degrees Celsius). Yet the apparently inky world appears to reflect almost none of the starlight that shines on it, according to a new study.
这颗巨大的行星大小同木星相当，被称作TrES-2b，运行轨道距离其恒星只有大约300万英里，表面温度达华氏1800度（摄氏980度）。然而，一项最新的研究表明，这个显然是漆黑一片的世界似乎丝毫没有将照射在它身上的光线反射出去。
"Being less reflective than coal or even the blackest acrylic paint—this makes it by far the darkest planet ever discovered," lead study author David Kipping said.
首席研究员戴维-基平说：“比煤炭或者是最黑的丙烯酸颜料反射性还小——这让它成为迄今为止发现的最暗的行星。”
"If we could see it up close it would look like a near-black ball of gas, with a slight glowing red tinge to it—a true exotic amongst exoplanets," added Kipping, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
他还说：“如果我们能近距离观察它，会发现它看起来像一个近乎黑色的气体球，略微带有淡红色的发光带——这在外行星中实属另类。”基平是马萨诸塞州坎布里奇的哈佛-史密松天体物理中心的一位天文学家。
NASA's Planet Detector
NASA的行星探测器
The Earth-orbiting Kepler spacecraft was specifically designed to find planets outside our solar system. But at such distances—TrES-2b, for instance, is 750 light-years from us—it's not as simple as snapping pictures of alien worlds.
环绕地球的开普勒空间站专门为寻找太阳系外的行星而设计。但是，在如此遥远的地方——TrES-2b距离我们有750光年——事情就不是给另一个世界拍个快照那么简单了。
Instead, Kepler—using light sensors called photometers that continuously monitor tens of thousands of stars—looks for the regular dimming of stars.
相反，开普勒要通过称为光度计的光线探测器，持续监测上万颗恒星，寻找有规律的恒星的减暗。
Such dips in stellar brightness may indicate that a planet is transiting, or passing in front of a star, relative to Earth, blocking some of the star's light—in the case of the coal-black planet, blocking surprisingly little of that light.
这样的减暗或许表明一颗行星正在通过一颗恒星（从其前面经过），相对于地球来说，就阻挡了那颗恒星的一些光线——在这颗漆黑行星的例子中，却令人奇怪地几乎没有阻挡光线。
Black Planet Spurs Dimmest of Dimming
黑暗星球显示出最轻微的减暗
When a planet passes in front of its star, the world's shaded side faces Kepler. But as the planet begins orbiting to the side of and "behind" its star, its star-facing side comes to face the viewer. The amount of starlight grows until the planet, becoming invisible to Kepler, passes fully in back of its star.
当一颗行星从其恒星前面经过时，它的暗面会朝向开普勒；而当它运行到另一侧，位于恒星“后面”时，它面向恒星的一面会朝向观察者。反射的恒星光线会增加，直到这颗行星运行到恒星的正后方，让开普勒观察不到它。
Watching TrES-2b and its star, Kepler detected only the slightest such dimming and brightening, though enough to ascertain that a Jupiter-size gas giant was the cause.
开普勒在观察TrES-2b和它的恒星时，只发现了很轻微的光线明暗变化，不过足以确定一颗跟木星体积相当的巨大气体球就是原因所在。
The light reflected by the newfound extrasolar planet, or exoplanet, changed by only about 6.5 parts per million, relative to the brightness of the host star.
这颗新发现的太阳系外行星——或者称为外行星——所反射的光线变化相对于其恒星的亮度只有百万分之6.5。
"This represents the smallest photometric signal we have ever detected from an exoplanet," Kipping said.
基平说：“这是我们所能从外行星上观测到的最小的光度信号。”
What's more, as the coal-black planet passed in front of its star, the starlight's dimming was "so small that it's like the dip in brightness we would see with a fruit fly going in front of a car headlight."
除此之外，当这颗漆黑的行星从它的恒星前面经过时，恒星光线的减弱是“如此之小，就像我们看到一只果蝇从汽车大灯前飞过时减弱的亮度。”
The Dark Mystery of TrES-2b
TrES-2b的黑暗之谜
Current computer models predict that hot-Jupiter planets—gas giants that orbit very close to their stars—could be only as dark as Mercury, which reflects about 10 percent of the sunlight that hits it.
当前的计算机模型预测：近距离围绕恒星运行的炽热的木星类行星（巨大的气体球）只能像水星一样暗，后者能反射照射到它上面的大约10%的太阳光线。
But TrES-2b is so dark that it reflects only one percent of the starlight that strikes it, suggesting that the current models may need tweaking, Kipping said.
但是TrES-2b却是如此地黑暗，它只反射了1%的光线。这或许说明目前的模型需要调整，基平说。
Assuming the new study's measurements are sound, what exactly is making the new planet's atmosphere so dark?
假设这项新研究的测量结果是可靠的，那么到底是什么让这颗新行星的大气如此黑暗？
"Some have proposed that this darkness may be caused by a huge abundance of gaseous sodium and titanium oxide," Kipping said. "But more likely there is something exotic there that we have not thought of before.
“有人认为黑暗可能是由大量充足的气态钠和钛引起的，”基平说，“但是更有可能是那里有些非比寻常的东西是我们从前没有想到的。”
"It's this mystery that I find so exciting about this discovery."
“这一奥秘是让我觉得这次发现令人鼓舞的原因。”
TrES-2b may even represent a whole new class of exoplanet—a possibility Kipping and company hope to put to the test with Kepler, which has so far detected hundreds of planets outside our solar system.
TrES-2b甚至可能代表了一类全新的外行星——基平和同事们希望用开普勒对这一可能性进行测试。到目前为止，开普勒已经在太阳系外发现了几百颗行星。
"As Kepler discovers more and more planets by the day, we can hopefully scan through those and work out if this is unique or if all hot Jupiters are very dark," Kipping said.
“随着开普勒日复一日发现越来越多的行星，我们希望能监测它们，并搞清楚出究竟这颗行星是个特例，还是所有炽热的木星类行星都非常暗？”基平说。
Meanwhile, the very darkness of the new exoplanet suggests perhaps a catchier moniker for TrES-2b, Kipping said. "Maybe an appropriate nickname would be Erebus"—ancient Greece's god of darkness.
与此同时，这颗新的外行星的漆黑或许给TrES-2b提供了一个更易于记住的名字，基平说。“也许俄瑞波斯是一个不错的绰号”——那是古希腊的黑暗之神。
The coal-black planet study has been accepted for publication in the Monthly Notices of the Royal Astronomical Society.
对于这颗漆黑行星的研究已经被《皇家天文学会月刊》采纳并准备发表。
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