In what universe is this hard science?
If scientific hypotheses have to be testable to be science (that is, it should be practically possible to prove them to be wrong), then this idea is only very tenuously scientific. To test it you have to irradiate the whole earth, or wait for the solar system to reach a different part of the galaxy. It's fair to say that the basic phenomenon can be demonstrated in a cloud chamber (that's what cloud chambers do), but quite a leap to go from that to the atmosphere of the whole Earth, with many other phenomena present. Nice idea, could be true, but like the man said the beer stays on ice for now.