4 large bright white lights in the night sky some flashing and 2 coming on together/no soundIN a clear night sky-Large flashing white lights on opposite ends of Imaginary straight line,lighting at different times, not simotaniously-- with simailar size strong white lights that came on together occasionally ,centered between the two flashing lights- see diagram below. Could not see shape of craft, but the lights were very large-- like headlights on a car that is at close distance. My husband is a private pilot, and although it's almost impossible to judge height and distance in a nightsky, his "Guestimate" is it was out 3 miles and at 3000ft. It was over Lake Michigan, so was not anything on the ground. The lights were probably 100 times larger than the stars in the sky. There was no sound. It was very exciting to see due to the proximity and size of lights. reported to coastguard