I would like your views on the subject of a hypernova.If a hypernova went off in our vicinity,would the gamma rays rip apart the gases in the earths atmosphere,so that nitrogen and oxygen would recombine as nitrous oxide,which would make it laughing gas,so we would end up all die laughing.and would the gamma rays change our genes over time?into a new spieces?i let u all ponder on this.
Let me start by saying that there was a magnetar that erupted about 10,000 lights away. It sent out magnetic forces strong enough that a shielded satellite looking the other way picked it up.
I had run into this subject a bit back elsewhere. I think that the novae would have to be within 10 lights or less for there to be any repercussions that would make it through the magnetosphere and earthís shielding atmosphere.
But should such take place, and close, then you would be looking at oceans boiling away. The earth would not be a habitable place. Luckily there are not many candidates within that sphere.
Sirius is a candidate to go nova but Iím afraid that it is a relatively young star and we will have to wait some time for it to be ready. It is a blue giant at about 7 lyís away. Farther out is Betelgeuse, a red giant, who is also a candidate to go nova. But it might be to far as to really have an effect on us.
very good points,but whats your opinion on the gamma rays,cosmic rays changing our genectic make up.do u think this can happen?
I don't think that "mutations" will take place if suddenly a GRB (Gamma Ray Burst) occurs somewhere in our stellar neighbourhood.
It is know that high-energy radiation can break apart DNA-strings, sometimes making them irrepairable (DNA helixes have a "restore" function in them: if one of the two pairing elements in a DNA helix gets knocked out of the chain, your body will replace it with an exact matching element (the pairs are constructed in such way that the two elements match)- if the complete pair is destroyed, the body just takes a guess for the replacement of the pairing elements, introducing mutations).
The most likely scenario is IMHO that the damage to your DNA and cells because of the intensive gamma-radiation is "beyond repair", making you ill (with probably deadly consequences). I'm no DNA/Cell biologist, but if I remember my highschool biology lessons correctly, this is more or less what happens :).
Millions of cosmic rays pass through your body every minute, even as we speak. Most do not hit anything. To give an example, there is a neutrino detector at the south pole. The cosmic rays will sometimes (rarely) hit an atom. When it does it will give off a neutrino. They do not detect many. Gamma rays will be mostly sheilded and blocked by the earth's magneosphere. If it was close enough you wouldn't have time to worry as it would be over rather quickly. Worry more about crossing orbits of comets and asteriods.
thanks wet1,thanks for details,i can now close this subject
It is true that some cosmic radiation is shielded by the earth's atmosphere, but high-energy gamma rays are able to make it to the earth (simply because they have those high energies, when they collide with particles in the atmosphere, they lose a small portion of their energy - but this energy is mostly abundant enough to let the gamma rays survive their entire passage 'till they reach the ground).
The neutrino detector you talk about does not directly detect neutrinos. Neutrino's hardly interact with matter (which is the reason why they survive their trip through the atmosphere). In the few occassions that they do interact with an atom (for example, in those giant tanks of water used for neutrinodetections), electrons or muons are created in the collision. Those particles can be detected more easily. The reason why neutrino detectors are in mine shafts or on the south pole is because the researchers don't want any cosmic electrons or muons reaching their detectors (and falsly reporting a neutrino collision in the watertank).