Discovered by Jim Scotti using the University of Arizona’s Spacewatch telescope (normally used to detect small asteroids near the Earth), 1991 VG seemed to be about 10 meters in size, but did not appear to be an asteroid. In a 1995 paper on 1991 VG, astronomer Duncan Steel (Anglo-Australian Observatory and University of Adelaide) noted “…strong, rapid brightness variations which can be interpreted as transient specular reflections from the surfaces of a rotating spacecraft.”
Fair enough — various man-made spacecraft have left rocket parts behind that could account for the object (and the thought that this could be leftover Apollo hardware immediately sprang to mind). But 1991 VG gets more interesting still given Steel’s finding that none of these known rocket bodies seem to have orbits returning to Earth at the time of the observation. That and the extremely close pass by the Earth suggested to Steel the possibility that 1991 VG could be an alien probe on a controlled reconnaissance mission.