1.In the early 1900s, astronomer Henrietta Swan Leavitt realized a class of stars called Cepheids pulsate, bright and dim, and every Cepheid that pulsates at the same rate has the same brightness.

1900 年代早期，天文学家 Henrietta Swan Leavitt 发现一系列名为造父变星，它们有规律地变亮和变，并且每个造父变星以相同的速率脉动就会有着相同的亮度。

2.Skowron explained that Cepheids are giant stars that are far brighter than the sun.

考伦解释说，造父变星是比太阳明亮得多的超巨星。