http://www.youtube.com/watch?v=hmJ-Qg3nFoc
Vegeta is a liar.
Goku cannot see the whole planet, and this would not be the only time a villain lied in DBZ, lol.
Also, ki blasts =/= physicality.
DBZ characters ability to work with ki makes them much more able to handle it than they can physical attacks. Their ki attacks are much, much more powerful than their physical attacks and yet their physical attacks are still plenty capable of hurting one another. So their durability is highly inconsistent or they can resist and combat ki.
No one in DBZ has ever demonstrated the physical might to destroy a moon, for example, quite the opposite, in fact. Heavy gravity and training weights are still a strain on their muscles, even when said weights would sit under a hundred tons, I'd expect characters like Goku to be able to bench press mountains, but DBZ stops several times to tell me 'no, no he cannot'. His ki attacks are absolutely herald level, but the rest of him is less impressive.