Mutternich replied on Permalink
Not exactly a new idea
In <a href="http://www.fantasticfiction.co.uk/e/max-ehrlich/big-eye.htm">this novel</a> a group of astronomers tell everyone the rogue planet is going to collide with the earth when they know it'll only come close, to get everyone to come together. It works. I think the author was a bit naïve, though.
P.S.: Spoiler apology.