Identification
Due to the absence of required navigation lights and the objects' unconventional flight characteristics, it seems unlikely that these were conventional aircraft. One of the more initially compelling possibilities is that these may have been military illumination flares; incendiary light sources suspended from parachutes which are intended to illuminate ground targets, sometimes seen where military aircraft are conducting exercises. Illumination flares have been suggested to be the likely central culprit of the similar but much more widely publicized Phoenix Lights event of 1997. However, in this case, video and witness accounts do not seem to present a slow, wind borne descent normally associated with illumination flares, and video and photographs do seem to suggest persistent relative order between the objects over the course of the event, moving about in a way inconsistent with gravity-bound objects retarded by parachutes.
The airspace over these dense suburbs are part of the immediate operating area of both nearby Midway International Airport and O'Hare International Airport (one of the busiest airports in the world) and is a controlled, Class Bravo airspace. In fact, Tinley Park is home to the O'Hare ATC backup radar system (an ASR-9 primary surveillance radar, Fac Ident QXM), which is also the active approach control radar for the Elgin TRACON facility. The controlled status of this busy commercial Class B airspace makes scheduled military exercises of any type unprecedented, unsafe, and unlikely, especially with respect to ground target illumination over a metropolitan area.
The multiple videos and photographs of the objects, along with supporting witness testimony as to the behavior of the objects suggests that this was not a misidentification of celestial bodies or other natural phenomena. Aerial suspension of lighted objects as a hoax could be considered a possibility, particularly with the event occurring on two consecutive auspicious dates popular with pranksters: Halloween. However, no known investigations by the FAA or other agencies were undertaken, nor any special public concern for safety expressed following the incidents, despite their potentially obstructive presence in a controlled commercial approach and departure corridor where lofting of obstacles would be taken very seriously and generally acted upon by law enforcement agencies.
No unexpected or uncorrelated radar tracks were publicly reported by the FAA in the wake of the events.
The origin of the objects is still unknown at this time.
Read more about this topic: Tinley Park Lights