I think that I remember reading somewhere that if, for example, a planet was 100 light years away from earth, then that means it will take that long for an event in that planet to happen in our planet? If that doesn't make sense, I can try to re-explain. Or, could someone just explain how light years actually work?

I've been wondering about this for a while

Ailurophile228 wrote:

I think that I remember reading somewhere that if, for example, a planet was 100 light years away from earth, then that means it will take that long for an event in that planet to happen in our planet? If that doesn't make sense, I can try to re-explain. Or, could someone just explain how light years actually work?

I've been wondering about this for a while

Borrowing some knowledge frrom "How Stuff Works" I found this:

Using a light year as a distance measurement has another advantage -- it helps you determine age. Let's say that a star is 1 million light years away. The light from that star has traveled at the speed of light to reach us. Therefore, it has taken the star's light 1 million years to get here, and the light we are seeing was created 1 million years ago. So the star we are seeing is really how the star looked a million years ago, not how it looks today. In the same way, our sun is 8 or so light minutes away. If the sun were to suddenly explode right now, we wouldn't know about it for eight minutes because that is how long it would take for the light of the explosion to get here.