Asteroids heading towards earth can we predict it early enough? what if it will destroy portion of earth or the whole earth?

asteroid flyby hmed 957 many more coming towards earth are we prepared? and can we survive? we need to escape earth
asteroid flyby hmed 957 many more coming towards earth are we prepared? and can we survive? we need to escape earth

The latest news I just read. On March 30th NASA scientist predict an asteroids about the size of a private jet will fly by near earth, closer to the moon to be exact, and it will miss earth by April 1st 2012. It’s no prank although it’s April fools, it did flew by earth “The asteroid 2012 EG5 was closer than the moon when it flew by Earth at 5:32 a.m. EDT (0932 GMT)” This indicate and proof that we can only predict asteroids this size hitting earth just only 3 days? what if it heading towards earth and we can predict 3 days ahead of time? This is scary isn’t it? Although it’s the size of a private jet airplane but the damage could be global. I’m not a scientist, but aren’t there a lot more asteroids out there that are flying all over the place in all directions, and if we cannot predict it early enough to prepare or if the asteroids is to big prepare for survival, what will we do? what’s up with the 5 stars laser nuclear gun that we have in space? do we really have it? and has it been tested proving that it will work destroying any asteroids heading towards earth? and a more scary questions, are those asteroids like the one just flew by, asteroids? or is it a spaceship of some sort alien spacecraft in disguise?