The Astronomy Thread

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Rime

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Distance is a bitch when it comes to space. Betelguese is 650 years away at the speed of light... so yeah. If it blew in the 1400s, we would be seeing it 'soon'.
 
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Captain Suave

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The real mindfuck about Betelguese is that it may have already gone supernova and we just haven't "seen" it yet.

Technically, "yet" needs quotes as well. "Now" is a concept relative to your own point as an observer in spacetime. Distance at lightspeed is certainly a useful approximation, but the deeper you dig the weirder time gets.

 
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Kirun

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Technically, "yet" needs quotes as well. "Now" is a concept relative to your own point as an observer in spacetime. Distance at lightspeed is certainly a useful approximation, but the deeper you dig the weirder time gets.

Isn't this somewhat of a semantics argument though? Like, I get that "now" is a different concept 650LY away, but nonetheless, their "now" would still occur 650LY "later" relative to our "now".
 
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Cad

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Isn't this somewhat of a semantics argument though? Like, I get that "now" is a different concept 650LY away, but nonetheless, their "now" would still occur 650LY "later" relative to our "now".

No because of time dilation, “now” 650LY away may not be 650 years ago depending on the observers speed, direction, etc. One observer traveling close to the speed of light may have observed the supernova 650LY away 10 years ago, and then flew into our space.

Space and time and “now” are sort of not concrete concepts as soon as you start talking about interstellar distances.
 
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Captain Suave

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Isn't this somewhat of a semantics argument though? Like, I get that "now" is a different concept 650LY away, but nonetheless, their "now" would still occur 650LY "later" relative to our "now".

Only in a very broad sense. Time progresses (slightly) differently everywhere based on local spacetime curvature. There isn't a time you can point to in Betelguese's chronology that precisely lines up with 650 years ago in ours. Read the wiki link.
 

Zindan

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I think it would amazing to have the chance to see a supernova light up the night sky in my lifetime. Sorry Betelgeuse, but I hope you exploded 500yrs ago.
 
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Borzak

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Who will have the best shot at reaching and exploring a distant star? Pioneer 10 will swing within .231 parsecs the star system HIP 117795 in the Cassiopeia constellation in approximately 90,000 years. And how long before one of these spacecrafts is hijacked by the orbit of one of these stars? It’ll be about 1,000,000,000,000,000,000,000 years.
 

LachiusTZ

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No because of time dilation, “now” 650LY away may not be 650 years ago depending on the observers speed, direction, etc. One observer traveling close to the speed of light may have observed the supernova 650LY away 10 years ago, and then flew into our space.

Space and time and “now” are sort of not concrete concepts as soon as you start talking about interstellar distances.

Not really, its just that the frames of reference arent fixed.
 

meStevo

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Love this shot of the Chinese lander on the far side of the moon.

ENaha5mUEAA1QSd


A few other images in this thread -
 

iannis

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Yeah, just like there is no universal grid and all objects are relative to other objects (there is no universal {0,0,0}) there is no universal now.

As a concept at interstellar distances it's not entirely meaningful. That follows from the observation that the transfer of information is not instantaneous.

We can take a telescope and peer into the furthest reaches of space possible for us to do that. What we see are mis shapen galaxies, we've decided that they're young galaxies, we understand this to be a historical record. All of that is consistent with the idea of the speed of light.

Now if that's what it is, how can that exist contemporaneously with us, the descendants of that process looking back into our own record? If we picked one mis shapen blob and pointed a space ship at it and traveled at the speed of light to it, would we ever get there? Ignore the expansion of space, we can account for that in our speed too with this magic. And what about the stuff past that?

The only possible way that it can exist is to discard this notion of the eternal, present, "now". And if it doesn't exist... well, how the fuck can we see it? It does exist in some manner.
 

Cybsled

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First person to bang in space. There won’t be a shortage of applicants I’m sure lol
 
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