Triangular object with intense red strobes near Yosemite; Mono LakeApproximately an hour after sunset, wife & I were unloading car at Yosemite campground in a valley with East- West orientation. Conditions were clear and cloudless, sky still midnite blue, not yet black, and not yet full of stars. We paused in our labors to admire the high jet contrails in the eastern sky, which still glowed a bit, catching the last of the light.Facing East, the object appeared from the South, first one, then two, and finally three tiny but intensely bright red lights, so bright and pure red, they made me think of a laser's intensity. These were NOT beams, but strobing point sources of a light wavelength so narrow it made me think of a red Helium- Neon or diode laser. These were unlike any civilian or military running lights either of us had ever seen; nothing to indicate port, starboard, or leading edge. They were arranged in a rough equilateral triangle, one corner either canted toward or away from us. As we quickly ran through the possibilities, we told each other to remember as much detail as possible; this was something unique! As the object soundlessly moved in a straight line from south to north, we each noted its appearance as it drifted over the contrails. My wife's impression was of a vague solid triangular object with red strobes at each corner floating ABOVE the contrails, which would make it enormous. My own impression was of a skeletal triangular structure with the same red lights at each corner, passing in front of them contrails, which would still render the object rather gigantic. There was a rather large gap between each light, notable because all planes must maintain high altitude over the Sierras, and thus their running lights appear close together.