If we geared up a new telescope tomorrow only to find one coming in from a previous blind spot as close as, say, one light-year away, we'd still have a few centuries before it would fry us, cause a cataclysmic collision within the solar system, and inflict some pretty intense gravitational disruptions. You're not going to be alive in a few centuries, though; that's the future's problem. And really, fuck those guys. All flying around in their precious jetpacks like they're better than you. They deserve what they get.