Sighting in Houston

I was sitting in a hospital parking lot waiting for a friend who was visiting his sick mother.
I was watching cumulus clouds drifting by when I spotted an object hanging overhead.
It appeared spherical and metallic and seemed as if covered by rust. It looked like a rusty ball bearing. It was hanging motionless at approx. 10,000 ft and was'nt drifting with the clouds like a balloon would do.
I decided to keep my eyes on this thing to see what happened.
It hung there for about 20 min. until an airplane came into view from behing me flying in its general direction.  The airplane appeared to be approx. 5000 ft below the object and did'nt seem to know it was there.
As the airplane came nearer to being under the sphere the object began to move vertically and accelerated until it disappeared from view.
Witness indicates that the date of the sighting is approximate.  PD