看到财富中国网上的一篇文章：

兼职一直是美国职场文化的一部分，虽然很多管理者都不鼓励这种生活方式。

Moonlighting has always been part of American work culture, though it's not a lifestyle many managers have encouraged.

兼职也能翻译成“moonlighting”吗？其中有什么典故呢？

My comments:

Moonlight means, yes, as you guess, moon light or the light of the moon. And the moon represents the night, as the sun represents the day.

People usually work during the day, right?

Right, but many workers find it necessary to moonlight, i.e. to work under the light of the moon.

And that means they’re working a second job, in order to make ends meet.

Therefore, it is an economic question, not a moral one. Americans moonlight. That is a fact, has always been. Managers may not like it, perhaps worrying that those who work during the night might be too tired to work the next day. But, the fact is, people moonlight mostly because they have to.