Eli5 When we look at a star 10 LY away, are we seeing 10 LY away or are we just seeing the light when it reaches us, or is it a mix?

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Title pretty much covers the question.

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Answer 1

So, when an airplane is overhead and it’s high, but not so high up you can’t hear it, it sounds a lot like the airplane is a lot farther behind than where you see it, right?

That’s because the light gets to your eyes way faster than the sound does.

So while you’re basically seeing it where it is in real time, the sound takes longer to get to you so you hear it farther behind.

Now stretch the distance out soooooooooooooooooooo far that like takes time to get to you, and it’s the same idea.