Science Buddies: "Ask an Expert"

I've been pondering for a while about shadows, as they're only really a defined pattern and are created by actual particles moving at the speed of light, and they also have a weight, there would certainly be a speed that could be measured here right?
Sadly concentrating is difficult for me, and I've only pieced together that it would be derived from the mass of the object casting the shadow multiplied by the speed of light and then divided by the surface area.
I'm sure this is a rather poorly asked question, but does any of this add up?

The Science Buddies Ask the Expert forum is for students in grades K-12 who need help with their science projects. There are other sites on the internet where your posts would be appropriate.
Thank you.