My son and I witnessed a circle of pale green lights drop from one point in the sky to another and disappear.

My 14-year-old son and I were driving home home from a basketball game.  In a relatively sparsely populated area about 5 miles south of Stanford on US 27 we witnessed a pale green circle of lights rapidly drop from the sky and disappear behind a low cloud.  It was so fast that by the time my son excitedly asked "What was that?" it was gone. I turned to him and said, "You saw it too?!"  The object was in the southeastern part of the sky.