Blue/green semi-circle light object near Washoe lake NV along 395

While driving southbound I noticed a bright blue light slightly east of the road, several miles away.  This is fairly hilly/mountainous terrain, and it was dark, so I assumed it was a light on a hilltop, or perhaps on a tower.  As I got close it became obvious the light was moving slowly from east to west.  I initially dismissed this as an optical illusion since there was no background other than dark night sky, but the road is pretty straight and the light clearly moved from the left to the right side of the road and got brighter.
I alerted the rest of my family in the car, who also witnessed the object.  As we got closer we noticed that there was a blue light on one side and a green light on the other.  As we approached I saw what appeared to be a semi-circle of light with blue on the left and green on the right (from my perspective).  I could never make out any detail other than the lights.  I would estimate the object was less than 1000’ AGL.  I am a pilot with over 20 years of experience in military fighters.  The light configuration was unusual and did not conform to normal aircraft position lights (green/red on wingtips and white tail).