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

斯考伦解释说，造父变星是太阳明亮得多的超巨星。

And since there were pulsating Cepheid stars whose actual distances we already knew, this let us build a cosmic measuring stick.

既然我们已经知有规律脉动的造父变星的实际距离，就给我们造出把宇宙测尺。

Now if two Cepheid stars are pulsating at the same rate, and one's dimmer than the other, that means one is actually farther away.

如果两个造父变星以相同的速率脉动，并且其中个个更加暗淡，就意味着更暗的那个更远。

If two Cepheid stars are pulsating at the same rate, and one's dimmer than the other, that means one is actually farther away.

如果两颗造父变星以相同的速率脉动，并且颗颗暗， 意味着颗实际上距离更远。

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 发现系列名为造父变星，它们有规律地变亮和变暗，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。

While studying what we now call the Andromeda  galaxy in 1923, Hubble realised that one of the stars he was looking at was a Cepheid variable  star – a type of star that blinks brighter and dimmer over the course of weeks.

1923 年，在研究我们现在所说的仙女座星系时，哈勃意识到他所看到的其中颗恒星是造父变星——种在几周内闪烁得更亮和更暗的恒星。

Cepheids are quite rare, but at least one of them is well known to us—Polaris, the pole-star, is a Cepheid.

造父变星非常罕见, 但至少其中颗是我们所熟知的 - - 极星北极星就是造父变星。