Stealthy rectangular object seen over Hernando, MSAfter finishing a late-night run, my girlfriend and I stopped to lie down on the track. While pointing out constellations we recognized, she motioned toward an object that momentarily obscured some of the stars from her view. I stood and watched the object after it passed overhead and noticed that it was rectangular, dark colored, emitted no illumination, very fast, and completely silent.It was difficult to determine its altitude, but seemed very low compared to surrounding commercial air traffic. No other aircraft seemed to be following it. The event lasted thirty seconds at the most, and the object moved in a linear path due North/Northwest. This event occurred in Hernando, Mississippi above a running track used by local schools.My girlfriend and I are young (in our twenties) and pretty well educated. I work as a chef in a nearby restaurant, and she is a reservist in the U.S. Air Force. She claims that the object displayed no characteristics of any aircraft she is familiar with.