Around 4:45pm central time, standing on the southwest side of springfield il, looking southwest. cool clear day with unlimited visibility. some high level clouds ~30k level. i observed a dark brown small object hovering in the distance at what appeared to be somewhere between 3,000 and 5,000 feet in altitude. it was really too small for me to see clearly, but it looked like a boomerang on its side with one wing broken half off. like an upside down "l". it was perfectly motionless from my vantage point for ~2 seconds prior to seeing it very rapidly shoot what appeared to be straight up. right after it started ascending, it emitted or reflected a brilliant bright blue-white light, similar to a welding arc. the light was very visible even though it was late in the afternoon. the "object" was not close to me, i estimate it was at least 10 miles away, likely further when it shot up. from the time i first saw it until it was out of sight was no more than 6 seconds. i heard no sound whatsoever from this. about 20-30 minutes later, i heard (not saw) loud jet aircraft (sounded like fighters) flying around for 10-15 minutes. i am an aviation buff and can identify all us aircraft made since wwii, some by engine sound alone. what i saw was definitely not an aircraft, it certainly wasn't a bird, wasn't an object bouncing off the atmosphere, or reflection. i don't think a human being could survive the acceleration i witnessed this thing do. it appeared to be much faster than mach 1 but left no vapor trail or shockwave or sonic boom that i saw. i didn't have a chance to take a picture or video.