It's not just X-ray jets that explode out of black holes (like the one at the center of out galaxy), there are also gamma ray jets, X-ray jets, visible light jets and radio wave jets.

Now scientists have decided they are all the same jet, with the same amount of energy released, but for some reason each has different amounts of energy coming out in different ways. So, sometimes x-rays, sometimes gamma-rays, sometimes radio waves....or a mixture.

There is a good chance one of these jets of high energy particles will hit Earth one day (the year 2012?). Scientists don't think so, because for the pathetically short amount of time they have been watching the center of our galaxy, they haven't witnessed it.