Aurora Borealis-like lights near Franklin Park in late 1970's

This event in my distant past has been a source of puzzlement for close to 15 years now, and the timing is actually one of the most bizarre aspects of the encounter as I will explain.
The dates and times are mere supposition, as the memory is still very vague.
I was attending NIU and driving back to school from my Mt Prospect home, at some point around 10:00 pm.  After passing the Curtiss Candy factory, off the 294 Hwy (heading South and looking off into the West), I noticed some strange lights that resembled the Aurora Borealis.  I recall stopping and discussing the lights with another woman who had also pulled over to the side of the highway (there were others, but I don't recall interacting with any one else).
The next memory I have that evening is being in the car miles away on the 5 Highway (now the 88) and driving back towards school, with approximately 2 1/2 hours unaccounted for.
However, the strangest aspect of this memory is that I didn't recall this incident AT ALL until over 20 years after it happened-and this is how the memory was sparked.  As a struggling writer in Hollywood, I use to make pitch meetings all the time, and from time to time I would see my ideas being produced.  I would laugh it off saying, "Aliens are sucking my brain," and on one occasion, I said that same phrase that I had used literally dozens of times—and the memory (though cloudy and with the missing 2 1/2 hr gap) came streaming back and actually scared me.
I know this is an extreme longshot, but Ive been hoping that someone might recall seeing those lights and help me at least put a day and time on the event itself.