Pop on turntable startup

I'm getting a pop sound through my speakers when I startup or stop my turntable motor. Anyone have any clue as to what this could be?

It's not really bothering me too much, but I would think that this might mean I'm getting excess motor or AC line noise picked up through my stylus or phono preamp or something.

I've tried to make sure all my power cables aren't touching any interconnects so I don't think that's causing it.

I've reposted my system so you can see what I'm working with.

Thanks in advance.
What kind of table do you have...sometimes its just normal operation...sometimes when the manufacturer addresses this little problem, they use a circuit to prevent you hearing it. In any event, dont let it trouble you unless the thump is quite loud...most times just forget it.
My dads VPI does it, we just got into habbit of muteing, probably is good practice anyway.
Thank you both for the help. I guess it's nothing to bother about.
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In some cases this can be eliminated by grounding the motor.
Look through all the threads on vpi. Someone had a similar problem and placed a capacitor in series with the switch which took care of the pop. I'm actually not sure if I read about it here or when I was googling. When I had a vpi with the stand alone motor I did this and the pop stopped.