And that explains the main sequence!

这就解释了主序！

Massive stars are hotter and more luminous, so they fall on the upper left of the main sequence.

大质量恒星更热，也更明亮，所以它们落在主序的左上方。

Because the star was born massive, it spent its hydrogen fusing days as a blue main sequence star.

因为这颗恒星在诞生时质量很大，它在氢聚变的日子里成为了一颗蓝色的主序星。

And the main sequence stars span from the upper left to the bottom right.

主序星从左上角横跨到右下角。

The HR diagram plots stars' luminosity versus temperature, and most stars fall along the main sequence, where they live most of their lives.

HR 图描绘了恒星的光度与温度的关系，大多数恒星沿着主序下落，它们大部分的生命都在主序中度过。

Stars spend most of their lives fusing hydrogen into helium, which is why the main sequence has most of the stars on it: those are the ones merrily going about their starry business of making energy.

恒星一生中的大部分时间都在把氢聚变成氦，这就是为什么大部分恒星都在主序上的原因：这些恒星在愉快地进行着它们那星光灿烂的制造能量的工作。