7 ms·

It's not like this is right on our doorstep but I'd still be more comfortable if this was happening more than 1480 light years away.

djcapelis 10y ago
So we could find out about it even later? :)
lucb1e 10y ago
Well whatever it is, we probably have 1000+ years to save ourselves right? If whatever caused it comes at us at 50% light speed, which sounds unlikely given how fast that already is, we'd still have 700 years. I'm pretty sure that if human's resources were suddenly all turned towards getting the hell out of here, we could certainly pull it off for a good part of the population in a few hundred years. Whether we'd eventually survive, after decades or centuries in space (before we manage to find and arrive at a new planet, if any), is something I'm less certain about, but I'd still estimate the odds to be fairly okay, especially with 1000+ years to prepare.
- jerf 10y ago
  "Well whatever it is, we probably have 1000+ years to save ourselves right?" No. That time has already passed. If we see signs that the star will go nova "in one year", we have one year, not 1481. The popular idea that we see "the past" in the sky is not really the best way to think about it. It is far more accurate to say that there is no such thing as "the" present, and what we see in the sky really is our present. The view that we're seeing "the past" is ironically perhaps less sophisticated than the more naive idea that it is simply our present we are seeing in the sky. (And at the moment, there aren't any other "presents" that we much care about.) The thing that really saves us is that even supernovas that far away can't really hurt us because of the inverse square law. A quick Google search shows one site estimating that a supernova would have to be 50 ly or closer or so: http://www.howitworksdaily.com/could-a-supernova-destroy-earth/ http://www.howitworksdaily.com/could-a-supernova-destroy-ear... Something would have to be beamed specifically at us, and the only natural phenomena I know that can do that are black holes and pulsars, neither of which seem to be what is at that star, and probably still wouldn't be powerful enough to hurt us at that distance.
  - gf263 10y ago
    I hate saying stuff like this but this blew my mind.
  - lucb1e 10y ago
    So what's the risk if it turns supernova in one year? As you say, it's 1500 ly away, not <50. You sound way more expert on this than me (I had no idea lightyears had a notation, ly, nor that supernovas are dangerous to us as far as 50ly away), so I'll assume what you say is accurate, but I still see no imminent threat. I'm also not suggesting we'd have the full 1481 years, since we don't see what's presently there but what was there, but as long as the phenomenon doesn't travel at the speed of light (and it doesn't, or we would be experiencing it already, since we can observe the effect) we still have time.
    - david-given 10y ago
      Finding information on this appears to be kinda hard, but it looks like the best estimate for the 'kill radius' of a supernova (i.e. will cause mass extinctions) is 30 light years. So this is about two orders of magnitudes away, which means the effect will be two orders of magnitude lesser. Eta Corina is a double star containing at least one hypergiant that's going to go supernova any epoch now, so it gets studied a lot. It's 7500 light years away and I believe it's judged not to be a threat, although there may be ozone layer damage and it's probably not healthy to be an unshielded astronaut. However supernovae appear to emit gamma ray bursts along their axes. These can travel very large distances. Eta Corina's isn't point our way, but Tabby's Star? Who knows. 1500 light years is basically point blank range for a GRB, so if one is coming our way that would be very bad news. Like, worse than mass extinction grade bad news.
      - jerf 10y ago
        "So this is about two orders of magnitudes away, which means the effect will be two orders of magnitude lesser." Inverse square applies here; moving 100 times farther away makes the effect 10,000 times less. (I have to say it "applies here" because people sometimes overapply the law. It only applies when something is spreading out in an even sphere. However, that applies to supernovae, or at least close enough.) You're right that I neglected gamma ray bursts. But it also doesn't seem like this star could be building up to that, since it requires conditions not evident there. (I'm just following up on my point, not implying that you claimed otherwise.)
- ridgeguy 10y ago
  Depends on how long ago "they" developed telescopes capable of viewing Earth with good resolution. We know in principle how to build such instruments. "They" may have watched the Romans build roads and sussed out their mining activities from atmospheric spectroscopy. Or much earlier, signs of agriculture. In which case they could be here...right about...just a sec, somebody's at the door....
  - lucb1e 10y ago
    My post was under the assumption it wasn't an alien lifeform. If that's what the person I responded to meant, then I see his/her point better. Still, if we finally found life, I'd prefer for them to be close rather than far. Curiosity killed the cat, but I'd rather learn about the aliens (if they are indeed arriving on our doorstep soon) than know they're too far away for either of us to make it in time.
- phyzome 10y ago
  700 years would be twice light speed; at 0.5c it would be 3000 years.
  - SolarNet 10y ago
    The math is wrong but not quite in the way you figure it. His point was that if the spaceship launched at the same time as the light left and the spaceship was traveling at 0.5c. So it would be 1480 years again (1/0.5 * 1480 - 1/1 * 1480).

djcapelis 10y ago

So we could find out about it even later? :)

lucb1e 10y ago

Well whatever it is, we probably have 1000+ years to save ourselves right? If whatever caused it comes at us at 50% light speed, which sounds unlikely given how fast that already is, we'd still have 700 years. I'm pretty sure that if human's resources were suddenly all turned towards getting the hell out of here, we could certainly pull it off for a good part of the population in a few hundred years. Whether we'd eventually survive, after decades or centuries in space (before we manage to find and arrive at a new planet, if any), is something I'm less certain about, but I'd still estimate the odds to be fairly okay, especially with 1000+ years to prepare.

jerf 10y ago
"Well whatever it is, we probably have 1000+ years to save ourselves right?" No. That time has already passed. If we see signs that the star will go nova "in one year", we have one year, not 1481. The popular idea that we see "the past" in the sky is not really the best way to think about it. It is far more accurate to say that there is no such thing as "the" present, and what we see in the sky really is our present. The view that we're seeing "the past" is ironically perhaps less sophisticated than the more naive idea that it is simply our present we are seeing in the sky. (And at the moment, there aren't any other "presents" that we much care about.) The thing that really saves us is that even supernovas that far away can't really hurt us because of the inverse square law. A quick Google search shows one site estimating that a supernova would have to be 50 ly or closer or so: http://www.howitworksdaily.com/could-a-supernova-destroy-earth/ http://www.howitworksdaily.com/could-a-supernova-destroy-ear... Something would have to be beamed specifically at us, and the only natural phenomena I know that can do that are black holes and pulsars, neither of which seem to be what is at that star, and probably still wouldn't be powerful enough to hurt us at that distance.
- gf263 10y ago
  I hate saying stuff like this but this blew my mind.
- lucb1e 10y ago
  So what's the risk if it turns supernova in one year? As you say, it's 1500 ly away, not <50. You sound way more expert on this than me (I had no idea lightyears had a notation, ly, nor that supernovas are dangerous to us as far as 50ly away), so I'll assume what you say is accurate, but I still see no imminent threat. I'm also not suggesting we'd have the full 1481 years, since we don't see what's presently there but what was there, but as long as the phenomenon doesn't travel at the speed of light (and it doesn't, or we would be experiencing it already, since we can observe the effect) we still have time.
  - david-given 10y ago
    Finding information on this appears to be kinda hard, but it looks like the best estimate for the 'kill radius' of a supernova (i.e. will cause mass extinctions) is 30 light years. So this is about two orders of magnitudes away, which means the effect will be two orders of magnitude lesser. Eta Corina is a double star containing at least one hypergiant that's going to go supernova any epoch now, so it gets studied a lot. It's 7500 light years away and I believe it's judged not to be a threat, although there may be ozone layer damage and it's probably not healthy to be an unshielded astronaut. However supernovae appear to emit gamma ray bursts along their axes. These can travel very large distances. Eta Corina's isn't point our way, but Tabby's Star? Who knows. 1500 light years is basically point blank range for a GRB, so if one is coming our way that would be very bad news. Like, worse than mass extinction grade bad news.
    - jerf 10y ago
      "So this is about two orders of magnitudes away, which means the effect will be two orders of magnitude lesser." Inverse square applies here; moving 100 times farther away makes the effect 10,000 times less. (I have to say it "applies here" because people sometimes overapply the law. It only applies when something is spreading out in an even sphere. However, that applies to supernovae, or at least close enough.) You're right that I neglected gamma ray bursts. But it also doesn't seem like this star could be building up to that, since it requires conditions not evident there. (I'm just following up on my point, not implying that you claimed otherwise.)
ridgeguy 10y ago
Depends on how long ago "they" developed telescopes capable of viewing Earth with good resolution. We know in principle how to build such instruments. "They" may have watched the Romans build roads and sussed out their mining activities from atmospheric spectroscopy. Or much earlier, signs of agriculture. In which case they could be here...right about...just a sec, somebody's at the door....
- lucb1e 10y ago
  My post was under the assumption it wasn't an alien lifeform. If that's what the person I responded to meant, then I see his/her point better. Still, if we finally found life, I'd prefer for them to be close rather than far. Curiosity killed the cat, but I'd rather learn about the aliens (if they are indeed arriving on our doorstep soon) than know they're too far away for either of us to make it in time.
phyzome 10y ago
700 years would be twice light speed; at 0.5c it would be 3000 years.
- SolarNet 10y ago
  The math is wrong but not quite in the way you figure it. His point was that if the spaceship launched at the same time as the light left and the spaceship was traveling at 0.5c. So it would be 1480 years again (1/0.5 * 1480 - 1/1 * 1480).