LightYear Visability?

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DaMarTri

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Amature here. I was just wondering, say I saw a star 1 light year away. When this star burns out, will it take a light year for me to stop seeing the light?
Also, is there a limited distance as to how far light can travel? Or could we even figure that one out?
 
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MeteorWayne

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That is correct.

The nearest star is ~4.3 light years away, so if it blinked out, we wouldn't know for 4.3 years.

Betelgeuse is 400-700 ly away, and may have already exploded as a supernova, and we just haven't found out yet!

Welcome to Space.com.

Wayne
 
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DaMarTri

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Thats cool. So that means a lot of the things we see now, may actually not exist any more. Interesting!
 
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SpeedFreek

Guest
Yes, for instance, when you see the Sun, you see it as it was around 8 minutes 19 seconds ago, and your view of the Moon is 1.3 seconds out of date!
 
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MeteorWayne

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To be excessively nitpicky, the current solar distance is 8 minutes, 20.9 seconds :) :) :lol: :twisted:
 
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kg

Guest
DaMarTri":w22qnxlk said:
Thats cool. So that means a lot of the things we see now, may actually not exist any more. Interesting!
Not really because stars have such long lives. Individuale stars last from millions to several billions of years. We can only see stars as far away as a couple hundred light years which is not very long compaired to the life of a star. If you know where to look in the night sky you can see light comming from the Andromida galaxy which is only about 2 1/2 million light years away. Even at that distance the majority of those stars are still shining even after their light has travelled all that way.
 
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nimbus

Guest
MeteorWayne":13kc6clm said:
To be excessively nitpicky, the current solar distance is 8 minutes, 20.9 seconds :) :) :lol: :twisted:
Nah, excessively nit-picky would be calculating the extra light travel delay from the tiny space expansion between us and nearby objects.
 
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DaMarTri

Guest
So anyway. 900 light years out. star burns out, it take us 900 light years to stop seeing the light.
Say there was intelligent life out there 900 light years away and they discovered Earth. Lets contact them they say. If they sent us a signal, by the time it reached us, the sender would have already died.
Sure we have recieved a message from another world, but I don't think you would be comunicating, just playing tag with messages.
(Does a satalite signal travel the same speed as light?)
 
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MeteorWayne

Guest
Hence the problem in communicating with other civilizations...light and radio are the fastest things in the Universe, and the time scales make actively talking useless.

Travelling is even worse, since accelerating anything with mass anywhere near the speed of light is enormously costly in terms of energy and danger. Our fastest space probes are but a tiny fraction of that speed.

And yes, all electromagnetic radiation from radio wvaes, infrared, visible light, ultraviolet, to X-rays and Gamma rays all travel at the same speed in a vacuum. That is "c"
 
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