The sphere moved in an absolute straight line just above the tree line.

I was in the backyard of my residence.  The residence is located in the pine woods of Bastrop County, about 5 miles north of the city of Bastrop.  The back yard was small, only about 30 x 50'.  There were trees surrounding the rest of the house and some small scrubs then larger trees in back of the yard.
 I had notice a passenger plane passing over just a few minutes before.  I was shooting a BB pistol when something moving at my left side in the air caught my attention.  When I first looked up, my immediate thought was that it was a dandelion puff then I realized a puff would be too heavy to fly.  Upon closer observation, it appeared to be a sphere in shape, of metalic construction.  It was traveling about ten to fifteen feet above the tree line in an absolute straight line without wavering.  The speed is estimated to be about 5mph.  There was a slight breeze which made me think that this object was under some kind of power or it would have wavered in the wind.
 I wanted to get my camera but thought that it would be out of sight by the time I retrieved it.  As the object passed at about a 10 degree angle from where I was standing, and about forty feet away, I opened fire with my BB pistol.  I had my doubts that I would hit it but felt like if I could, I may be able to alter its course.  I shot at it several times and then observed it as it went out of sight beyond the trees in the front yard.
 I have relived this event many times, wondering just what it was that I observed.  I have never observed another unexplained object since that time or even before.
Witness does not indicate year of the sighting.  PD