4 Bright lights of indeterminant altitude traveling south to north spaced evenly apart.

These lights appeared to be two to three times brighter and larger than Venus in a clear nighttime sky. Because the altitude was indeterminant it's impossible to estimate how large they were, the speed with which they were travelling or the distance apart from each other. They were travelling in what appeared to be a straight line at a stable rate of speed. The movement was more suggestive of a series of helicopters but the lighting suggested otherwise There was no flashing or pulsing, just a steady bright illumination of a single color. The color temperature was warmer than what one normally sees with aircraft and appeared to be similar to tungsten lighting (about 3,400 degrees kelvin)
While driving underneath the line of lights, we lowered car windows in order to try to hear the sound of the aircraft. But, they were completely silent suggesting either a high altitude or silent propulsion method.