I am a professional pilot. I viewed this in flight on a departure from Teterboro Airport. The aircraft was at an altitude of 6,000’ MSL on an approximate 020 heading. I was looking out the left front cockpit windshield towards a 300 heading in the direction of Northwestern NJ and upstate NY. The object was streaking downwards almost vertically and was dark green in color with a lighter whitish/green tail. It lasted at heat 2 seconds.