I can't tell you how devastated I am by this news.
I love this guy. I credit him with giving me my interest in sci fi.
When I was in grade school, about grade 4 I think, we got a huge shipment of new books for the library come in. I snuck into the store room during lunch and rummaged through the box and found "A Fall Of Moondust". The cover was just the freakiest thing I'd ever seen. I think it was a UFO half buried in the surface of the moon. From then on, I was hooked.
RIP Mr Clarke. You will be sorely missed.