[jjacob]

Originally Posted by Dangerzone

i ment precisely how old..............we have it down to a few billion years

and even those numbers are guesses..............educated guesses, but guesses none the less

And with good reason, because it's hard to have a common definition of when exactly a planet is "born" - is it when the gasseous elements start to come together, is it when it's "roundish" for the first time etc. And those are not educated guesses, they're precise estimations based on solid evidence (carbon dating etc.) - there's a difference. The generally accepted estimate is "4.55 billion years (plus or minus about 1%)", and that's accepted by brilliant minds around the world with far more knowledge about these matters than either of us probably will ever have