Okay, I need some discussion. I love love love reading about the universe and such. All the stars and planets out there, it’s amazing to me! But I’ve never been able to understand light years. Like, we could be looking at something in the sky and be all “Ooooh that’s a bright star!” But it’s 100 light years away and for all we know the star is actually dead and we are seeing the light as it had been traveling to us but died previously. This just goes right over my head. How do we just determine all these objects in the sky are so far… how do we know how far the light from thst object has been traveling? Please help lol! How do we also see planets so far away… I know we have amazing technology but damn… that’s insane to be able to see objects just so far away! I also think there must be some form of life out there. There’s no way we are the only planet with something living on it! Thanks for your input!
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A light year is a measure of distance, it’s how far light travels in a year. Light travels at ~186,000 miles per second, so that times 60 seconds per minute times 60 minutes per hour times 24 hours per day times 365 days per year equals 1 light year being about around 5.866 trillion miles.
So now think about taking a picture and then running as fast as you can to your friend’s house to show them. It takes a while, right? It’s the same thing with super powerful telescopes, imagine the thing the telescope is aimed at is taking a picture and sending it to Earth at the speed of light, and that image has to travel to the lens of the telescope. That time could be anywhere from 1.28 seconds (the moon ~239,000 miles), to 20 minutes (Mars at ~207.5 million miles), to 45 minutes (Jupiter at ~500 million miles), or beyond.
The telescope is seeing things super far away, but the further away it is, the longer it takes for the light the thing has produced to get to a place where we can see it.
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