En route from London Stansted Airport, UK to Helsinki Intl, Finland with Czech Airlines, Boeing 737.Approximately forty miles south of the Finnish Aland Isles I witnessed an unfamiliar object travelling at a high rate of motion.At the time I would estimate that the aircraft was between 28,000-32,000 feet in altitude, which inturn I would estimate the object in question was at an altitude between 22,000-24,000 feet.I first noticed a faint tangerine glow in the corner of my eye, and turned to face it in curiosity. I was stunned to see a large distorted ball of flames travel beneath the aircraft in a smooth and powerful motion.I would describe the object as a ball of intense, dark flames no smalled than a Douglas DC-3 followed by a thin 'tail' of flickering flames which may have measured upto 150 feet in lenght. I believe the object did indeed have leave a contrail.((NUFORC Note: Witness elects to remain totally anonymous; provides no contact information. PD))