沙漏星云喷射瞬间如同人眼

　　The sands of time are running out for the central star of this hourglass-shaped planetary nebula.

　　在这一酷似沙漏形状的星云内，“时间之沙”即将从中央星之中流逝殆尽。

　　With its nuclear fuel exhausted, this brief but spectacular closing phase of MyCn18 - better known as the Engraved Hourglass Nebula - occurs as its outer layers are ejected.

　　随着其本身的核燃料的消耗几近枯竭，被称为“沙漏星云”的MyCn18的最外层开始朝外喷射，它这一短暂而又壮阔的生命也行将结束。

　　Located 8,000 light-years away from Earth in the southern constellation Musca, the sun-like star's core is in the process of becoming a cooling, fading white dwarf.

　　“沙漏星云”MyCn18距离地球8000光年，位于南天苍蝇座，这颗类似于太阳的星核进入了逐渐冷却的阶段，并慢慢变成了一颗白矮星。

　　Astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae in the mid-1990s, including this one.

　　上世纪九十年代中期，天文学家们运用哈勃太空望远镜拍摄到了这一星云的众多图像，其中便包括了这一张。

　　Delicate rings of colourful glowing gas - nitrogen-red, hydrogen-green, and oxygen-blue - outline the tenuous walls of the hourglass.

　　红色氮气、绿色氢气和蓝色氧气这些彩色发光气体共同组成了这个形状与沙漏极其相似的星云。

　　The uNPRecedented sharpness of Hubble's image has revealed surprising details of the nebula ejection process.

　　哈勃太空望远镜拍摄到的图片相当清晰，以至于揭示了这一令人惊讶的星云喷射过程。

　　And it is these that are helping scientists to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebula.

　　在图片的“协助”之下，科学家们有望揭开揭开行星状星云复杂的结构，以及其对称性背后的谜团。

　　MyCn18 was discovered by Annie Jump Cannon and Margaret W Mayall during their research on an extended Henry Draper Catalogue, an astronomical star encyclopedia compiled between 1918 and 1924.

　　1918年到1924年间，Annie Jump Cannon和Margaret W Mayall在扩充恒星百科全书“亨利-德雷珀目录”的过程中发现了“沙漏星云”MyCn18。

　　The astronomers described it as a small faint planetary nebula, but the march of technology allowed scientists Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory to capture this stunning image using Hubble in January 1996.

　　起初，科学家们将之形容为一小团昏暗的星云，但随着天文研究科学技术的发展，1996年1月时，科学家Raghvendra Sahai和John Trauger利用哈勃望远镜拍摄到这张令人叹为观止的图像。

　　MyCn18's hourglass shape is thought to have arisen from the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles.

　　MyCn18之所以呈现出沙漏的外形，是因为一个缓慢扩张的云团里迅速向外冲去的恒星风造成的，其“赤道”附近的云团密度要大于两极。