Working nightshift at the local hospital, stepped outside with a coworker for a cigarette and when returning to the building noted what loked like a "falling star" but brilliant - it illuminated the parking lot and left a blue/green trail behind it. The sphere itself was approximately the size of a small car and brilliant white in color with a blue "aura" around it. It flew extremely close to the ground with absolutely no sound that we could hear. It seemed to, for lack of a better description, suddenly burst in speed leaving a ring of sparks and appeared to accelerate before disappearing out of view. Once again, no sounds - not a boom, not a crash, nothing. Like it just vanished.I do not believe it was a metorite, and if it was, it was surely larger than any I've ever witnessed in my life - and I've seen plenty. (Leonids, for example) and it appeared to literally fly, not fall.As an amateur astronomer, I'm accustomed to seeing things like the space station, satellites, comets, falling meteorites and the like - this was something distinctly different in both appearance and behavior.