Board Thread:Questions and Answers/@comment-35097614-20180517011323/@comment-396366-20180517123237

Not really sure which specific scenario you are referring to, because not every planet is like Earth. If you strictly want the energy to destroy Earth, then yes, option B would probably be the general way to go; you have to exceed the gravitational binding energy of a planet to blow it up. Basically, Vegeta's Galick Gun in his fight against Goku during the Saiyan saga would be at least 2.487×1032 J if not more. Planet Vegeta, on the other hand, would have a far greater gravitational binding energy, given its surface gravity of 10 g. As for Namek, we really have no information to go off of, but we could assume that it is similar to Earth due to the fact Bulma had no issues surviving on it without any sort of life support.