I bird-watch and watch airplanes off my balcony on the 3rd floor. it was about dusk with some daylight left when an object blazed across the sky just west of route 83 & irving park rd. it had almost no arc to it's travel, it was about parallel to the horizon and was traveling north to south. it looked like a neon green flare with a sputtering tail end. i saw the patch of sky where the object originated, it came out of nowhere. it didn't appear to be fired out of anything, didn't originate from the ground and it disappeared after covering a distance of approximately a mile and a half. if it was a firework, it was unlike any firework i've ever seen. if it was a shooting star, it didn't have the distinctive streak and made absolutely no noise, especially for being so close. i don't believe in ets visiting earth and this was just south of o'hare airport with airplanes taking off near this thing all over the place, so there has to be some explanation. since i wanted to know what it was, i scoured google and the descriptions of "green fireballs" are dead on. eerily so. this object was witnessed also by my significant other who read over this description and gave her approval.