Clear night sky: No cloud. I was taking my dog out before bed. I witnessed a very bright white light travelling soundlessly North to South. The light was many times brighter than the surrounding stars, considerably brighter than Venus: clearly artificial. No navigation lights were visible. It took approximately a minute and a half to travel from one horizon to the other. I lost sight of it when it reached the Southern horizon.Planes often travel overhead, but even high altitude planes can be heard, and their navigation lights are usually easily seen. I thought that it may be the International Space Station. It was much too bright and fast to be a satellite. I went back in the house and checked the location of the ISS online, but it was currently above the Eastern seaboard and not visible from my location. I checked a flight-checker website for planes in the area, but the closest plane was on a different heading,at 36000 feet and approximately 50 kilometers to the North of me, whereas the light vanished to my South. It was not consistent with any aerial phenomenon I am familiar with. If it were a plane, it's brightness and speed would suggest a lower altitude, and yet it was utterly silent and I could make out no navigation lights in spite of the fact that I witnessed it in several profiles: Approaching me, passing overhead and from the 'rear' as it receded from me.I am struck by my inability to clearly identify it. I am unable to even give a 'likely' explanation that fits what I observed.Eric Gilmer