Quote Originally Posted by Radar View Post
You would feel any change in gravitational pull only after the nova blast scrapes your planet clean. As long as the roughly spherical expanding cloud of plasma is within your orbit, nothing essential changes.
I think you'd notice it slightly before that. The net gravitational force might still be pointing int eh same direction at the same strength, but I think you'd start to notice if there are significant components pulling you in other directions as well, even if they sum to the same thing.

But semantics aside, trying to trigger a supernova so you can do something funky gravitationaly on the planet you're on is just really, really stupid :P