Kalidescope of colors under triangle shaped craft

Specific Location:  Missoula, Montana,  Obrien Creek Road, approx. ¾ mile west of Big Flat Road on the west side of town.
Weather :  Dark, overcast , wind from WNW approx. 25-30 with gusts  Temp:  35/40 degrees as best I remember.  Topography:  Narrow lightly populated canyon with a  two-lane dirt road serving residents.   High steep mountain on the southern side of the canyon, less steep on the north side.   Road to top of  ‘hill/mountain’ both sides  300 – 400 feet.  The road from Big Flat Road deadended some 2 plus miles more or less going west.
Was restless that night, nothing on TV to gather my interest.  Took a walk to  clear  my mind.
Walked off my property to O’Brien Creek Road and went east towards town.  I could see the lights of town as usual..   Traveled on foot, gravel road, little over quarter mile, then turned around to go home.   Wind was picking up, noticed the clouds were showing ‘star breaks’  where I could glimpse a few stars here and there.
Got to the driveway to go up to my house and ‘felt’ strange for some reason.   Thought that is odd.  I looked west up Obrien Creek Road and the sky was pitch black, no star breaks.  Stood there maybe 30 seconds and all around me above, it suddenly went pitch black, like somebody turned out the lights.
Turned and looked towards town,  could still see the lights of town reflecting off the clouds in that direction.  Looked up and I could barely detect that something was moving above me.  Rush of ‘what the hell’ of course.
Then as I looked up I saw an oval shaped light in a kalidescope of colors moving slowly over me in an easterly direction.  Tried to process all this without much luck.  The colors were moving around inside the oval, not rapidly, not at a snails pace.  My term for it was ‘a normal pace’, don’t know for sure where that came from  In a few more seconds the colors were gone,  and I could see a huge black triangular object moving over me and toward the east.  The black on this object was blacker than the surrounding ambiance, therefore it did have shape and movement.  It was dead silent as it moved, and it covered more than the height of the canyon tops both north and south of me.  Distance from the north and south tops I estimate to be over ¼ mile.
Then, it was gone.
I stood there,  trying to sort it all out.  Ha.
Walked up to my house, took off my jacket, and looked at my hands, they were beet red.  Went into the bathroom, and my face was beet red as well.  Both hands and feet were itching but I thought it was from the harsh wind.
Something told me, take a shower, now.  So I did, a long one, lots of soap.  Then, I sat around and went to bed early .
Next day, a couple of my co-workers asked me how I got a sunburn.  I mumbled and left it along.
The next day the redness had faded a lot, and the next day it was gone.