Explanation: What would it look like to circle a black hole? If the black hole was surrounded by a swirling disk of glowing and accreting gas, then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. The featured animated video gives a visualization. The video starts with you, the observer, looking toward the black hole from just above the plane of the accretion disk. Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere — inside of which lies the black hole’s event horizon. Toward the left, parts of the large main image of the disk appear brighter as they move toward you. As the video continues, you loop over the black hole, soon looking down from the top, then passing through the disk plane on the far side, then returning to your original vantage point. The accretion disk does some interesting image inversions — but never appears flat. Visualizations such as this are particularly relevant today as black holes are being imaged in unprecedented detail by the Event Horizon Telescope.
Tomorrow’s picture: swan and galaxy
说明: 绕行黑洞会看到什么？ 如果黑洞的周围，环拱着一个由辉光吸积气体组成的吸积盘，那么黑洞强大的重力会把盘面辐射的光折回来，形成非常奇特的景观。 这部主题动画，就把这种景观视象化。 动画以观察者的视角为开头，从稍高于吸积盘的位置眺望黑洞。见到环绕在中心黑洞周围的一个纤细光环，它标示出光球所在的位置，光球之内为黑洞的事件视界。 在视野左侧的主盘面影像，因为旋向观察者而显得较明亮。 随着影片持续，观察者旋到黑洞上方俯视，接着再旋向远侧穿过吸积盘，然后再回到最原先的视点。 影像中，吸积盘经历了一些很有趣的影像倒转，但看起来从不是扁平的。如今，像这类的视象化特别关键，因为事件视界望远镜，正以前所未见的解析能力拍摄黑洞 。
明日的图片: swan and galaxy