Very close to zero since: #1 There are lots more "amateur" astronomers looking for these things. It's more likely to be found by one of them before the government finds it. #2 Someone would leak it.
I think we need a rock to hit and flatten a city before we finally start getting serious about getting off this rock of ours. Dublin is good enough. A big city but like the rest of Ireland a blip on the "anything important to Earth" radar screen.
No, it has to be somewhere in the United States. Otherwise the U.S. media & public will only put pressure on the government for a few weeks maximum before moving on to the next shiny object, like maybe a parrot who can recite all of Luke's dialogue from The Empire Strikes Back. If it hits a major city in the US that the media cares about, we might get six whole months of proper pressure to get the space program on track.
Okay...... A city in America that is like Dublin in terms of blips on radar screens....... Detroit. That will work.
Conservatively, I'd guess half the Congressmen on that committee believe the Sun orbits the Earth. They will certainly develop an answer.
500 kilotons is as big as you can get with a fission device. Anything above that is fusion based. http://www.nuclearsecrecy.com/nukemap/ map lets you play with nukes. 500 Kilotons will fuck up any city. Good thing this blew up so high in the air. Edit: Almost forgot...... Don't have to worry about radiation. But still you're having a seriously bad day if one blows up in your city.
I was going to provide a comment on this news, but I'll bet everyone can guess its gist. And I have a pretty good idea how the subsequent discussion would unfold.