Witnesses were in a six-seat airplane, flying from Pella, IA to Minneapolis, MN.The three witnesses were seated on the right side of the airplane. Wit A was in copilot seat, wit B in rear, Wit C was between them.Two sightings occurred. Sighting 1:Witnesses were WitA and WitC. Occurred at about 7:30 PM.Flying due north, 20 miles south of Hampton, IA.Altitude was 3700 ft, level, airspeed 140MPHapproaching Hampton for refueling.Wit A attention caught by glint of metalic object at 12 O'clock low. Wit A est that object was 400 ft away, 300 ft below.Object was moving on N to S path, antiparallel with aircraft. Wit A est that it took less than 3 seconds to move 3 miles as measured against section lines on Iowa farm fieldsObject was round and shiny. There was a red light or lens on the top of it.Size was approximately that of a quarter at arm's length.Wit A turned head to follow object. Gone in a second, lost to sight behind head of person sitting behind. Last seen at 5 O'Clock low.Wit B also saw object, but I do not yet have his report.Sighting 2 - 8:00 PM - 2 seconds in length:Witnessed by all three wits.Airplane flying from Hampton Iowa toward Minneapolis.Wit B first saw the object (do not yet have his report)Wit A heard Wit B 'squeal'. Turned to look back and saw object in rear window of airplane.All 3 wits observed object in rear window, receding rapidly into distance until lost from sight.Object was primarily visible as a red light against the darker ground. Wit A says that metalic/reflective surface associated with light. Wit B says that only light was visible.