Thanks BFSGrad for the explanation . I do not know how a Patriot missile finds its taget, but a balloon is stationary . made almost all of thin synthetic fabric and gas (Helium or Hydrogen) , the payload is rather small and it is not poducing any heat, so IR will be useless. But maybe it has contrast camera or laser detection.?
Just listened of the Pentagon briefing , did not say much other that it is apparently at 60.000ft, so much lower than I tought, and is able to manoeuvre , which kind of surprises me , up and down yes of course, but laterally ? .It was identified as a surveillance balloon . At one polint he said it was the size of 3 buses, but not saying if this is the payload or the balloon itself.