At or about 0534 hours i and my wife were doing our morning routine soak in our hot tub. looking up directly overhead at extremely high altitude i noticed several lights traveling at high altitude from the south in a nne (north northeast) direction. there were banded mid level clouds at approximately 10-15 thousand feet. i pointed out the lights to my wife, noting that they were flying in a linear formation. she also observed them in the area of the sky that i indicated. we watched as 10-14 lights appeared from the cloud cover. the lights were spaced approximately 5-7 seconds apart. at first i thought they might be airliners from the denver international airport (we live about 12 miles from the airport) but these lights were very high altitude and were traveling approximately 500-1000 mph at altitude. the lights displayed did not blink like normal aircraft visibility lights but i did see some different colors (red, blue, white) on some of the lights. this may be because of the high altitude. we observed no contrails and all lights were traveling in the same direction. we both could see normal aircraft lights in low altitudes north of us that were apparently from dia (denver international airport) and were moving far slower than the observed high altitude lights. my wife is a nurse and i am a former us army r&d photographer and retired federal law enforcement officer. as a photographer i worked in many military r&d units such as the aviation research and development labs at ft. eustis, va; combat development and experimentation command, hunter ligget mil res, ca and at white sands missile range nm. i am an amateur radio (ham) operator with a general class license. these lights were unusual in appearance and altitude. one of my thoughts is that this was some us air force training flight but the trailing formation is something i'm unfamiliar with (possibly a high altitude penetration formation?). after considering that aspect i was unsure of the actual nature. i've been around both usaf, us navy, us army and usmc flights of various aircraft and all of this was not something i've seen before. my wife was somewhat upset and she stated, "that's really odd" and decided to get out of the hot tub at that point in time. she repeatedly asked me what the lights were and i admitted that i didn't know for sure. i have reported this because in all my experience of unusual military "events" i have never observed this type of formation.