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Actually, there's at least one. There are essentially cosmic death rays that travel at the speed of light, undetectable until they reach us. I wish I could reme

Actually, there's at least one. There are essentially cosmic death rays that travel at the speed of light, undetectable until they reach us. I wish I could remember what they're called, but they're generated by black holes consuming stars, and they have far more energy than the asteroid that killed the dinosaurs. It's implausible that one will hit us, but if you're looking for a scientific and logical motivation, it's a possibility. Also, colonizing mars is a necessary step toward avoiding what happens when our star reaches the end of its life. May as well start while we have the opportunity.

TheSpiceIsLife 9y ago
Is it plausible that a cosmic death ray from afar could be so tightly focused that it didn't irradiate the entire inner solar system but only Earth?
- grondilu 9y ago
  I'm no astrophysicist, but I think I can answer this one. No, it is not plausible. Most bodies in the solar system easily fit into a hundred astronomical unit radius sphere. The nearest star is four light-years away, and a light year is eighty-six thousand astronomical units. The ratio between those distances is 2530[1]. It'd be like hitting a meter size target from more than two and a half kilometer. Pretty good shot, and we're talking about Proxima centaury (which, last time I checked, won't go supernova anytime soon) and the distance between say Sedna and the Sun. If we were talking about an accuracy more of an astronomical unit, more like the distance between Earth and mars, then we're talking about a centimeter sized target. Thus a gamma-ray burst would have to be insanely narrow to hit Earth and not mars. Not to mention how ridiculously unlucky we would have to be then in order for it to be precisely aimed at us. 1. https://www.wolframalpha.com/input/?i=four+light-year+divided+one+hundred+astronomical+units https://www.wolframalpha.com/input/?i=four+light-year+divide...
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TheSpiceIsLife 9y ago

Is it plausible that a cosmic death ray from afar could be so tightly focused that it didn't irradiate the entire inner solar system but only Earth?

grondilu 9y ago
I'm no astrophysicist, but I think I can answer this one. No, it is not plausible. Most bodies in the solar system easily fit into a hundred astronomical unit radius sphere. The nearest star is four light-years away, and a light year is eighty-six thousand astronomical units. The ratio between those distances is 2530[1]. It'd be like hitting a meter size target from more than two and a half kilometer. Pretty good shot, and we're talking about Proxima centaury (which, last time I checked, won't go supernova anytime soon) and the distance between say Sedna and the Sun. If we were talking about an accuracy more of an astronomical unit, more like the distance between Earth and mars, then we're talking about a centimeter sized target. Thus a gamma-ray burst would have to be insanely narrow to hit Earth and not mars. Not to mention how ridiculously unlucky we would have to be then in order for it to be precisely aimed at us. 1. https://www.wolframalpha.com/input/?i=four+light-year+divided+one+hundred+astronomical+units https://www.wolframalpha.com/input/?i=four+light-year+divide...

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