Craft flying over head in the woods.

Walking in the woods and heard a weird humming noise.....sounded like our electric generator or something, but lower. Then we saw a weird shape move very fast and low across the trees. It looked like a circle that came to a point at the top, with the point being at the rear of the craft. It went really fast over us but then turned around maybe a couple thousand feet down. We got really scared and turned to run but it just flew over us again. Interestingly, the noise stayed at the same sound level regardless of how close the craft was. Also, there was a faint light coming from the entire craft, just barely enough the distinguish it from the night sky. We tried to take a few pictures as it was leaving but I don't know how they will turn out.