且由于在另一个星系中的单颗“造父变星”的亮度就足于使其被观测到，所以它们是测算类似星系距离的首选工具。
And, since individual Cepheids are bright enough to be seen in other galaxies, they were the first tool used to estimate the distances to such galaxies.
他们发现了差不多800个造父变星，一种用于准确测量距离的特殊变星。
They discovered almost 800 Cepheid variable stars, a special class of pulsating star used for accurate distance measurement.
造父变星是可靠的宇宙距离(测量)里程碑，其完整的一个光变周期直接反映了星体的本质光亮度。
Cepheids are reliable cosmic distance mileposts. The interval it takes for the Cepheid to complete one pulsation is a direct indication of the stars'; s intrinsic brightness.
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