1·See photos of new planetary nebula.
查看新的关于行星云团的照片。
2·The Eskimo nebula is clearly a planetary nebula.
爱斯基摩星云显然是一个行星星云。
3·L the Ring nebula in Lyra is the best-known of the planetary nebulae.
l天琴座中的环状星云是最著名的行星状星云。
4·The Cat's Eye nebula (NGC 6543) is one of the best known planetary nebulae in the sky.
猫眼星云(NGC 6453)是天空中最著名的行星状星云之一。
5·Our own sun will blossom into a planetary nebula when it dies in about five billion years.
大约50亿年后，我们的太阳死去时，也会变成行星状星云。
6·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。
7·The spoke features seem to indicate that the Helix Nebula is itself an old and evolved planetary nebula.
辐射线的特征似乎说明了螺旋状星云本身的古老；历经了行星状星云的演化过程。
8·A planetary nebula is an expanding cloud of gas ejected from a star that is nearing the end of its life.
行星状星云一个由来自中心濒临死亡恒星所释放出的气体组成的正在膨胀的星云。
9·Hence, it is rare that an open cluster survives long enough for one of its members to form a planetary nebula.
因此，一个疏散星团很少能够存活到它内部的某个成员变成行星状星云。
10·Also known as Abell 21, this Medusa is an old planetary nebula some 1, 500 light-years away in the constellation Gemini.
也被称作阿贝尔21，水母星云是双子座中一个1500光年远的年老行星状星云。