While traveling north on I-57 at 11:16pm on Saturday, April 5, 2014, my wife initially spotted a descending bright object off the front, right of our car. That would place it north and east of our position. She exclaimed “do you see this!” and I looked toward her side of the windshield seeing the quickly descending object. It appeared to be a spherical shape with the bottom brightly lit in a bluish-white light. Not a beam but bright like the moon (which was seen clearly toward the west-southwest of our position). The object appeared to descend straight down behind a tree line where we lost visual contact. The total duration of my sighting was perhaps 2-3 seconds and my wife observed it perhaps a second or so more. We were so astonished we immediately called my brothers who were also traveling (but in Missouri) and told them of the sighting. This was one of the best unexplained contacts I have ever had as the night was crystal clear with unlimited visibility. Temperature was about 43deg. We discussed options as to what it may have been, but can only conclude it is not explainable by the usual air vehicles. I am a retired US Air Force officer with years of observing military aircraft.