导读：沙漏星云（MyCn18），还有一个动人的名字“天空之眼”，因天文学家通过哈勃太空望远镜观测距地球8000光年远的外太空时，它像极了上帝凝视的眼睛。据悉，MyCn18内部原子能已耗尽，“天空之眼”将消失，最终冷却成白矮星。MyCn18由Annie Jump Cannon和Margaret W Mayall在扩编HD星表（1918-1924）时发现，沙漏形状的成因是MyCn18在低速膨胀的云气之内有高速膨胀的星风，而云气在赤道的密度又比两极高。
Exhausted: Located 8,000 light-years away from Earth in the southern constellation Musca, MyCn18's core is in the process of becoming a cooling, fading white dwarf
Astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae in the mid-1990s, including this one.
The unprecedented sharpness of Hubble's image has revealed surprising details of the nebula ejection process.
And it is these that are helping scientists to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebula.
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.
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.