We were outside in backyard around 9:15 pm and noticed the slow-moving craft. It was very large, with pulsating red lights around exterior that outlined shape of craft. The lights were in rotating/pulsating in a circular pattern around craft. It flew very low, made no noise, and at the end of sighting, what appeared to be 2 black helicopters with red lights arrived to escort craft. It moved slowly through sky approximately 300 feet above us. The craft was massive, about size of football field. It moved from southeast to northwest. It then rapidly descended and appeared to land when it reached a private airfield that is called Skyline Ranch. At first, we wondered if it were a plane, but it was completely silent. Then we thought it may be 9helicopters flying in tight formation, but we discarded that theory when the two black helicopters arrived and we could determine the difference. It followed the same flight pattern as many of the planes around here, but was definitely not a plane as it was simply too massive.The dogs were visibly upset and wanted to be indoors, and now we are wondering why we can't find any other reports of the object. Feelings before and after exist of frustration that no one else saw it or reported. We are a little consumed by trying to find out what it was.