On the night of august 11, at about 10:20pm, i was in the backyard taking the dog out. we live on the north shore of lake whatcom in washington state. it was a beautiful, clear night and the temperature was comfortable enough for a t-shirt. the view of the lake and sky at this time of the evening is always spectacular and i especially enjoy looking at the star field, which suffers from little light pollution. facing south, i noticed to my right at about 30 degree above the horizon and, judging by the angle from my position, due east of the lake, a brightly lit orange strobing object. somewhat larger than a star. my initial assumption was an aircraft. the flightpath from seatac passes over the hills in that direction. i looked for the usual navigation lights, but only saw orange flashes. what was obviously a plane was approaching from farther south, and easily identifiable as such. i concluded that this was something else. the plane was perhaps a few percent larger, in relative terms. during the approximately five minutes i watched it, it strobed about three times per sec. i also detected what i initially thought was movement relative to its general, very slow, northward movement. it appeared to jump back and forth a short distance, relative to my position. less than 1% of arc, but at what i concluded was a distance greater than the seatac flightpath, which was a few degrees lower than the object, this would be a significant distance. as it moved, left to right, the apparent size increased, giving the appearance that in the rightmost position it was either closer or larger. it moved back and forth several times: larger on the right and smaller on the left. always strobing. an additional detail is that the movement appeared to leave a trail between the two positions, also orange and distinctly narrower. in the right position, it appeared as two objects: larger on the right, connected by the “trail.” it never changed color, always a light orange with no other colors present. during the time i observed it, it moved slightly north relative to the peak of the hills to the west. at the beginning of the preceding paragraph i say “initially thought was movement” because in the rightmost position, there was still a light at the leftmost position. the distance between the positions of the lights would eliminate any convention aircraft explanation. it was too great unless the aircraft was massive in size. i went inside to get my wife for verification, but when we returned it was gone, or at least was not exhibiting the previous behavior.