Slow moving ball of pulsating light surrounded by fog aura. Changed speed and direction quickly leaving a halo of "exhaust"

All three witnesses were immediately drawn to a slow moving ball of light. Despite being a clear cloudless night the object was surrounded by a hazy fog and had alternating or pulsating light. After hovering in the atmosphere the craft grew brighter and with an explosion of light left a ring of fog in it's wake as it moved rapidly across the horizon before changing direction again directly away from Earth. It maintained an aura of fog around it at all times. The halo of exhaust hung in the atmosphere for approximately 15 minutes growing larger and larger as it dissipated.