This is a very tricky stage to pass. Your goal is to aim at or near the rock.
Power Activation Point
As you are about to hit the meteor rock, shoot your laser gun down so that they will bounce on the metal triangles, killing all the birds at four corners.
First Shot Result
Now it’s pure luck whether or not your pig or the rock will travel to the center which kill the center two birds. Try it multiple times until you can pull it off, however it is a really hard stage that requires a ton of luck and patience.