Albert Einstein famously said that "imagination is more important than knowledge". If I may add a humble something to the words of wisdom by a genius, knowledge sometimes helps one's imagination.
Actually, knowledge can serve as the secure base (as was described by John Bowby) for one's imagination. Knowing for a fact that the sun is burning hydrogen to make helium can set one to imagine a lot of things on an idle afternoon.
No knowledge, no imagination.
One could go quite far in one's imagination based on scanty information. When I was a kid, I used to imagine a lot, because in those days there was relatively little information about anything that you cared about.
With the advent of information age, there is a danger that imagination is suffocated. To avoid death by knowledge, one should have a strong pair of legs. By jumping from the springboard of knowledge, one can dive into the ocean of unlimited imagination.