Kaboom!!!

[Rocketman]

It seems to me that Namek is SMALLER than the Earth because of the way its depicted during fights and its shorter year.

The length of a planet's year has nothing to do with its size.

[Senzu_Bean]

IIRC Namek is larger than Earth.

[Bussani]

Well, from a real world perspective nothing in DB would make sense.

That's true, so anything I say is in a, "Man, I find this interesting," sort of way.

Still, is there any official size correlation between the DB Earth and Namek? It seems to me that Namek is SMALLER than the Earth because of the way its depicted during fights and its shorter year.

There's nothing official as far as I know. Oddly, I always assumed Namek was bigger than Earth for some reason, but I have nothing to back that up.

As Rocketman pointed out, the size of a planet wouldn't affect its year. A year is how long it takes to orbit its star--though since planet Namek has three, I have no idea how that works.

If that is the case then it would take more energy to destroy the Earth than to destroy Namek.

The energy needed to blow up a planet depends on its gravitational binding energy, not its size. But since Namek seems to have gravity similar to Earth's, you're right, it would be easier to destroy if it were smaller. In fact, if it were half the size, it'd be about eight times easier to blow up. Coincidentally, if it were twice the size of Earth, it would take eight times more energy to blow up!

That said, I still think its more of a matter how you do it then brute force. Buu exploded the Earth by expending all his energy to explode himself. Freeza destroyed Namek by busting its core. I don't believe Freeza could have done the same Buu did as he uses a specific technique to get to the core. He doesn't just blast the planet.

In real life, it always comes down to requiring the same amount of energy in the end. Say you could cut the Earth in two; if you then wanted to accelerate those two halves away from each other, it would require the same amount of energy as it would to just blow the planet to smithereens. Pretty interesting, really. But maybe it works differently in Dragon Ball. In Dragon Ball, when things get holes in them, they explode for some reason. I cite Planet Namek and Piccolo Daimao as examples of this phenomenon.