Bubbles

On Saturday 11th of October 2003, I borrowed a wife for the evening and we were sitting around the barbecue discussing the price of fish in Moscow.  Not that we knew anything about Russian fish but being Kiwis, we're naturally experts at everything.  It was still light, about 7.30 pm, when something very strange happened.      In space of a minute, four little bubbles appeared.  The biggest was about two centimetres across.       The first and biggest circled the table and drifted to the ground where it disappeared.      The second lodged on the riser of the concrete step and contained what looked like a italic Z.  I had a close look and it wobbled with the air pressure I created.  The Z was in the middle and I could see around it from all sides.      The third drifted around and settle on the arm of a white plastic chair.  It contained a tiny white blob in the middle.      The fourth bubble was the smallest and my part-time wife lifted her hand and managed to get it to settle on her fingers.  It contained a large blob of what looked like a greasy yellow substance.  Somewhat dismayed she tried to rub it off on the edge of the table.  It popped and the yellow substance took a few minutes to disappear without leaving a residue.      My borrowed wife is very imaginative and suggested we had been invaded by aliens from a far off planet.  I tried all the normal, 'take me to your leader or we'll call the White House and have you invaded because you're obviously armed with weapons of mass destruction and thus a danger to paranoid politicians,' sort of stuff.  But they didn't respond. Maybe they couldn't speak American and had never watched Star Trek?      Very soon it grew dark and both remaining bubbles reflected in the full moon and moved slightly in the soft breeze.  After half an hour the bubble on the chair disappeared but left a bright point of light that took another half an hour to fade.      The bubble on the step remained in place for two hours but seemed to change to an italic M before it disappeared.  An extremely bright light remained and lit a small proportion of the step and even cast a tiny shadow.  The light still shone when I blocked the moon light.  We could even see a white substance on the step.  Another hour and it had faded, melted, dissolved or whatever.  By morning there was no evidence that the bubbles had ever existed.        I had been drinking wine but the weeks most intimate wife in arms didn't drink and witnessed the same thing and had even held a bubble on her finger.  There were no neighbourhood kids to blow bubbles and I'm damned if I know what caused them.  Has anybody got a plausible explanation?  And NO, I wasn't suffering from marital guilt.  Just sore knees.  But that came later.