wow
Im almost to scared to talk on the forum now. "impossible , not possible" always thought they meant the same thing.
lol they do in that context - remember this is the English Language we are talking about and writting like "No its not possible" is a double negative so that has the affect of changing the meaning to be "it is possible" got to love the english language. As Zedman240 pointed out it is more technically correct to state
"No, it's impossible" and even "No, it's not possible" works but "no its not possible" does not due to missing punctuation = double negative, I believe the second one works as the comma make the No and Not appear in different clauses so there is no double negative.
Hell and I failed English + I am a Kiwi and I know how you ozzies love to take the piss (read with a kiwi ascent) about how we speak. From your "Friend in the Fridge"

or for those younger TV viewer "Beached as Bro" (have not been to Oz for almost 12months so not sure about any new ads)