Wide black line with pointed front moving across night sky in MNAppeared in western sky as a dark, cloud like line contrasting the light clouds under a bright moon. Appeared to have a triangular edge to the front of phenomenon, although it was not definitive, or sharp. It moved across the sky seemingly eating the clouds as it went, with constant speed remaining on straight line course for the duration of viewing. This "object" or phenomenon was being shadowed by an aircraft with a white flashing light which seemed like it was traveling supersonic due to the engine sound delay, and it seemed to be losing ground to the black streak. The tail of this streak dissipated quickly and it looked to have a reasonably constant size throughout the viewing. Length maybe 75-100X the length of the aircraft and about 50x wider. Took about 25-30 seconds for the dark streak to cross the sky with the trailing aircraft in view for abut a minute. The clouds seemed to dissipate after this event for a few minutes revealing the stars and moon only for the clouds to move back into place about 10 minutes later.