The World of "Why?"

Having a 2 1/2 year old is quite interesting.....trying and frustrating sometimes, but definately interesting. Luca has entered the world of the why, as I like to call it. Everything you ask or answer to him, he seems to reply "Why"? Now, I like the fact that he is curious about the world around him and want him to always ask questions about everything and anything--that is how they learn about things and life. However, the humorous part (and sometime trying part) is the long string of whys.
For example:
Luca: The sun out today?
me: no, it's cloudy
L: Why, where's the sun?
me: The sun is behind the clouds
L: Why?
me: it is cloudy and rainy
L: Why? where's the sun?
Me: behind the clouds
L: is it getting dark?
me: no, just cloudy
L: why?
and on and on.....

It just is a bit interesting and after like the 10th why--I sometimes run out of answers.

It also makes me realize all the things I don't know and maybe (or not) should know.