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Old 03-18-2015, 08:28 PM   #8
Johnny1A.2
 
Join Date: Feb 2007
Default Re: THS Rogue Planet

Quote:
Originally Posted by malloyd View Post
I'm fairly sure an anti-comet would be detectable *too* far out to be very interesting.

Annihilation gamma ray peaks are very distinctive. Unless I've seriously blown the calculation, a chunk of antimatter a meter across moving at a typical stellar proper motion should be hitting enough interstellar hydrogen for the annihilations to be detectable with our recent gamma ray telescopes at half a light year. We might not have more than a few thousand years warning....
Good point. Of course that could just be incorporated into the McGuffin of it: "Why did we not pick this signal up sooner? Why did we only start picking up the annihilation signature when it's a year out?"
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