So far, I’ve worked on one movie in which the Earth is destroyed. In Titan A.E., a mysterious alien race called the Drej show up one day and blow up the Earth because…
…well, I don’t actually remember the motive. Plot wasn’t the strongest aspect of that movie.
What’s important is this: aliens did it. So if scientifically-minded viewers questioned the physics of how exactly the Earth was obliterated, I could simply point to the semi-transparent Drej and say, “With their superior technology, far beyond anything we can imagine!”
It’s a lucky thing that Titan A.E. had villainous aliens, because it turns out that destroying the Earth is extraordinarily difficult. With this site, Sam Hughes examines 18 possible methods for “geocide” — a terrific word that you just don’t get to use very often. His conclusion? Aspiring supervillains need to be patient, or very lucky, because mere mega-wealth won’t guarantee you the chance to smash the Earth to smithereens.
Keep in mind that Sam focuses strictly on physically destroying the planet. Merely making it uninhabitable is several orders of magnitude easier — and we’re already well on our way!