Luminous circular orb disappears into nothing

Stepping outside my front door, I glanced to the south and saw a large luminous circle which quickly after I looked at it seemed to move in an eastward direction. 
As it moved it seemed to go behind something, as it gave the appearance that the circle and light were disapperaing behind something. 
There did not appear to be anything else there. 
It was a clear night with some clouds, but none where I saw the circle.