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Does that make the assumption that the nova's energy is distributed evenly? Because I believe there are gamma ray bursts that are quite directional, and can if

Does that make the assumption that the nova's energy is distributed evenly? Because I believe there are gamma ray bursts that are quite directional, and can if pointed at us cause harm far further than that. (IANA astronomer...)

colechristensen 4y ago
No, a gamma ray burst pointed at us within several thousand light years could cause a mass extinction event. There are a couple of candidates for mass extinctions which might have been GRBs. They are very rare though.
- pencilguin 4y ago
  Still, it would be safer to get out of the thick part of the galaxy as soon as possible. Life in a galaxy risks many different hazards. I don't think we have ruled out magnetars nearby enough that a minor starquake would sterilize the whole solar system. Aggressive neighbors might want to use up our valuable Kuiper Belt objects on their own projects. Maybe start by shifting the orbit of the whole solar system out-of-plane. (I guess that would be done by electromagnetically stimulating the sun to produce a polar jet for a few million years.) That provides our distant descendants another 100M years to alter the orbit further so as not to just plunge back in on the other side. But even without, the risk would grow back to our present level for only (say) 10M out of each 100M years, strictly an improvement. Orbital plane maneuvers are infamously expensive in delta-V. Spending the following 100M years increasing our galactic orbital radius might put us in the outskirts before crossing again, if we did not actually escape entirely. We might also be able to put off by a few billion years the sun itself sterilizing the planet, using the same apparatus. We could only hope it would not be abused to destroy us itself. Andromeda isn't due for another 4.5 Gy. Presumably its central black hole and ours will merge shortly thereafter, maybe sterilizing the whole galaxy? I am content to leave worrying about that to others.

colechristensen 4y ago

No, a gamma ray burst pointed at us within several thousand light years could cause a mass extinction event. There are a couple of candidates for mass extinctions which might have been GRBs. They are very rare though.

pencilguin 4y ago
Still, it would be safer to get out of the thick part of the galaxy as soon as possible. Life in a galaxy risks many different hazards. I don't think we have ruled out magnetars nearby enough that a minor starquake would sterilize the whole solar system. Aggressive neighbors might want to use up our valuable Kuiper Belt objects on their own projects. Maybe start by shifting the orbit of the whole solar system out-of-plane. (I guess that would be done by electromagnetically stimulating the sun to produce a polar jet for a few million years.) That provides our distant descendants another 100M years to alter the orbit further so as not to just plunge back in on the other side. But even without, the risk would grow back to our present level for only (say) 10M out of each 100M years, strictly an improvement. Orbital plane maneuvers are infamously expensive in delta-V. Spending the following 100M years increasing our galactic orbital radius might put us in the outskirts before crossing again, if we did not actually escape entirely. We might also be able to put off by a few billion years the sun itself sterilizing the planet, using the same apparatus. We could only hope it would not be abused to destroy us itself. Andromeda isn't due for another 4.5 Gy. Presumably its central black hole and ours will merge shortly thereafter, maybe sterilizing the whole galaxy? I am content to leave worrying about that to others.