I was on my way back to Chicago Midway on a Southwest flight when I saw this outside my window seat. We were traveling east and it was several miles to our north, but impressive nonetheless. From my perspective, it was looked a lot like pictures you always see of comets. For the few seconds I was able to see it, it was burning white hot and got more intense just before it broke up into 3 pieces and quickly disappeared from site.
I'm not sure what it was, but it made for a fantastic show!