I think that this picture is cheating as I used a lid to draw around to make the circle. Nic and the lady who droned on during her dull youtube video disagree.
We'll worry about drawing perfect balls later on though...
I can't explain exactly what is wrong with the above picture, but I know that it is not quite right.
We don't have any balls or sphere-y objects in our flat, so I've found some useful images from the web which might help.
These 2 diagrams (above) are basically both saying the same thing.
As are the 2 below.
