Th comet will be knocked out of its orbit, where it will careen towards...
...New Jersey, prompting Bruce Willis and his crew of scruffy yet loveable oil rig workers, plus his annoying, whiny daughter to be sent to the comet to blow it up with one nuclear bomb to make it split in half just in the nick of time!
And along the way they will dock at a Russian space station, where they will meet a stereotypical cosmonaut, who will then have his whole space station fall apart so he has to come along with them.
My God, it will be like a movie....