Astronomers have captured the first image of a black hole, heralding a revolution in our understanding of the universe’s most enigmatic objects.

　　The picture shows a halo of dust and gas, tracing the outline of a colossal black hole, at the heart of the Messier 87 galaxy, 55m light years from Earth.

　　What are black holes?

　　Black holes were first predicted by Einstein’s theory of general relativity, which reimagined gravity as the warping of space and time by matter and energy.

　　The equations predicted that, beyond a certain threshold, when too much matter or energy is concentrated in one place, space and time collapse, leaving behind a sinkhole through which light and matter can enter but not escape.

　　At first these were thought to be mathematical oddities, rather than real astronomical objects, but in the past century overwhelming evidence has confirmed that black holes are out there.

　　The edge of the black hole is defined by its so-called event horizon. This is the point at which escaping would require something to travel at faster than the speed of light – which as far as we know nothing does – so it is the point of no return.

　　Black holes are surrounded by an accretion disk of dust and gas, orbiting at close to the speed of light. A lot of this material is destined for oblivion, although some of it is ejected as powerful jets of radiation.

　　什么是黑洞?听霍金讲述黑洞~

　　首张黑洞照片揭晓，人类第一次看到黑洞的视界面!它由有效口径相当于地球直径的望远镜阵列观测到，经过2年“冲洗”完成。

　　北京时间4月10日21点整，天文学家召开全球新闻发布会，宣布首次直接拍摄到黑洞的照片。这张照片来之不易，为了得到这张照片，天文学家动用了遍布全球的8个毫米/亚毫米波射电望远镜，组成了一个所谓的“事件视界望远镜”(Event Horizon Telescope，缩写EHT)。

　　这颗黑洞位于代号为M87的星系当中，距离地球5300万光年之遥，质量相当于60亿颗太阳。

　　大家在平时阅读科学新闻、科普书籍以及观看科幻电影的时候，也经常能看到黑洞的样子，但其实都是根据科学理论推测出来的，并非直接观测。2014年，由诺兰执导的科幻电影《星际穿越》大热，在这部影片中，光环笼罩下的超大质量黑洞——“卡冈图亚“(Gargantua)令人心生敬畏，这里的黑洞形象是使用计算机模拟出来的。在著名理论物理学家吉普·索恩的指导下，这里的模拟已经非常接近真实了，但毕竟还是模拟，这次是玩真的了。

      为什么能给不发光的黑洞拍照?

　　这些年，黑洞这个名词频频出现在媒体报道中，想必很多人都已经对它有些了解。恒星级质量的黑洞是由大质量恒星演化到末期核心发生引力坍缩而成。中等质量黑洞和大质量黑洞的形成的具体方式目前还没有定论：可能是由小黑洞合并形成，也可能是由黑洞通过吞噬物质逐渐形成，还可能是由大量气体物质直接坍缩形成。

　　黑洞给人印象最深刻的印象就是吞噬一切，甚至光线。如果是孤零零的黑洞，我们真的是没办法采用电磁波手段进行拍摄了。