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If I were in space looking at a star that just started producing light that was two light years away. Would I be able to see the light coming towards me?

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  • $\begingroup$ No. How would you? $\endgroup$ – Asher Jul 19 '15 at 5:05
  • $\begingroup$ No. You would have to wait two years. $\endgroup$ – march Jul 19 '15 at 5:06
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You can't see the light coming towards you. But you can see it as soon as it reaches your position. That means, that if you're in space and there is a star which is 10 times far than the speed of light in seconds. And if that star emits the light "now", then you won't be able to know that whether the light is emitted "now" or not. Instead, after 10 seconds, you'll be able to see the light that was actually emitted by that start 10 seconds earlier.

This also means that you'll be looking at something that happened 10 seconds ago "at that star". If you ever took a telescope and looked at the sky, then you'll actually be looking at the lights that were emitted few seconds/minutes(depending on the power of telescope, whether it can see that far or not) ago.

Good luck!

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  • $\begingroup$ Just to note, our own sun is over 8 light-minutes away. Other objects in our solar system range from light-seconds (the moon) to light-hours (the outer planets) from us. The nearest star is four light-years away. $\endgroup$ – Asher Jul 19 '15 at 6:19
  • $\begingroup$ Exactly! We can also say that the sun that we see is actually an image of sun that had already happened in past, i.e. 8 minutes ago. $\endgroup$ – Anoneemus Jul 19 '15 at 6:23

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