At roughly 7:00pm I was traveling westbound on I-74W in central Illinois. Near Brimfield I spotted a spherical white object the size of a golf ball in the southern sky moving in a northwesterly direction. Initially I assumed it was star, but upon further examination it was not that high in the sky. I kept driving and the more I watched the object it seemed strange. It was one solid light with no other lights around it. I called my father to tell him what I was looking at because by this time I had been watching it for 10 minutes. He started to ask me how big, how high the object was. It was hard to say and then an obvious commercial airplane flew behind and above the object. Being a commercial airliner I assume that it might have been flying at 30,000 ft and was maybe 30-50 miles away, the object I would guess at an altitude of 5,000 feet and 5-10 miles away. A size comparison if the airplane was anywhere from 80-220ft in length the object had to have been I guess at 50-100ft. The object was still traveling in a northwest direction in the southern sky from my perspective, it seemed to be a moving roughly the same pace as me for 25 miles. As I continued to watch and drive the object for several minutes appeared to be in the shape of a boomerang, I assume this was because of the angle I was viewing it from. I was driving to Burlington, IA so I exited onto 34West in Galesburg, IL. For 25-30 minutes I had been watching this strange object and I felt compelled to call 911 not out of fear, but for the desire that if this was ���something��� I wouldn���t have been the only one to see it. I pulled over on the highway and did call Galesburg���s 911 and they did say they would send a car to check it out. I continued to drive and was in between Galesburg and Monmouth, IL heading west. I pulled over again because the object was directly in front of me and was much closer than it had been before. I got out of my car to see if I could hear any noise and it was silent. I did also at that time call my father again and had him get a phone number for MUFON from their website, I briefly talked with someone and told them what I was seeing. The object at this time appeared it was maybe 3-5 miles away and maybe 2000-4000ft in altitude. I got in my car and continued trying to get a closer view, but the object then increased its distance from me. I arrived in Monmouth and stopped at a gas station to view the object so I could have a stationary point of reference. The object appeared further away and was either stationary or traveling away from me. I started to question what I was seeing wondering if my eyes are playing tricks on me is it just star, so I went into the gas station to buy some cigarettes. When I came out the object was still in the same place, I started to question myself again, am I just looking at Venus or some other star. I got back onto the highway again and the object appeared to come closer again briefly. Within seconds the object gained greatly in altitude and distance disappeared into the sky heading northwest and into orbit. This sighting lasted overall 70-85 minutes. While I was on the highway of course there was traffic and maybe some other people saw it also, I hoped that driving 50mph when the speed limit was 65mph some people might notice the object also. This was a very crazy sighting of something I can���t explain.