My wife and i were driving north on rt 29 from silver spring at about 9 pm on christmas eve. my wife was driving. we just reached the intersection with rt 198 when i noticed a bright white light suddenly appear in the sky. we were heading in a north easterly direction. then a white but translucent light emanated from the white light for about 2 seconds and then the light moved rapidly and disappeared from sight. i joking said to my wife i just saw santa. she asked what i was talking about and i explained what i just saw. i described what i observed without ascribing a reference to a ufo. the experience was somewhat surreal. we discussed the event. my wife is familiar with constellations and planetary movements and could not connect my observation with anything she knew. i have seen other ufos, mostly hovering lights that then move rapidly but i have never seen anything like this episode. the most striking aspect was the "trail" that appeared before the rapid acceleration. the trail was not like a vapor trail and became almost triangular in shape before the object moved and disappeared. the object moved in a southerly direction for an instance before disappearing.