At about 2206 EST, I was standing on the second floor deck on the back of my town home watching the stars when I spotted a large, pulsating multi-colored light to the west-south west, about 245 to 250 degrees by compass. From my vantage point, the light was stationary and appeared to be hovering just above tree-top level, west of I-270 toward Point of Rocks and Harper's Ferry. The light itself was about three or four times larger than a star, but smaller than the moon, and was circular or orb shaped; it was flashing what appeared to be red, blue, white and green-colored lights. I was likely too far distant to hear any sounds from the craft, even if it was emitting them. Though I realized some of the flashing colors are similar to aircraft navigation lights, the strange, rapid, pulsating quality of the lights, combined with the apparent low altitude and size of the object led me to signal a nearby neighbor, who was fiddling on his phone below me on the street. We are not unaccustomed to state police helicopter landings and searches in our area; I also figured the light might be some firework or perhaps a transformer exploding.
While trying to direct my neighbor around the corner of his town house block, so that he could observe what I was seeing, I tried turning on my camera, which I luckily still had in my back pocket. As I struggled to guide my neighbor to a good vantage point, since his ground-level view was still obstructed by some houses across the street, I finally was able to get my camera to turn on. I snapped a few photos, most of which didn't turn out well, and then captured a brief, albeit extremely shaky video on my phone(the craft did not move, only my hands.) Throughout this period, the object seemed to remain stationary, hovering and flashing. After taking these photos, I continued to work on my neighbor who was still in the wrong position. As he finally began moving in the right direction to get a clear view of the object, the pulsating from the light faded and by the time my neighbor saw it, it had 'shrunk' down to a single white light. As it did, it began moving southward, parallel to I-270, it appeared, just above tree level. I subsequently ran down to street level, since my view was now blocked, joining my neighbor at the corner to watch the craft as it cruised off the south.
After it disappeared from our view, we were joined shortly thereafter by two other neighbors, who were disturbed by my shouting. Another small white light flying the same flight path (north to south parallel to I-270), flew along the tops of the some distant trees at about the same speed as the other craft. There was no flashing, pulsating or abnormal size with this light, however, it seemed to be a regular aircraft.
I submitted a FOIA report to the FAA, asking for radar data from the area at around that time. It may very well have been a plane or helicopter whose lights were distorted by the weather. I've seen a lot of aircraft, though nothing quite like that.