It's caused by sunlight directly hitting the front of the camera lens; most people refer to it as "lens flare" (read more here). On SLR cameras, it can be somewhat controlled by using a lens hood...not much you can do about it on P&S cameras except hold something up (a hat, or your hand, etc) out of the frame of the picture to block the sun from shining directly on the lens.
Well you learn something new every day. Thanks!