bottom of a huge aircraft hovering directly over the yard.

I was working night shift at the switchboard. I went outside on the porch, because I heard a humming, low, pulsating noise-like that heard in a transformer yard.I stepped ontp the porch and looking around, I didn't see anything. I went back inside, but continuing to hear the noise, again went out to investigate. This time I looked up. Whoa-WHAT IS THAT?I was huge! It was gray metallic, and was blocking the stars. It was about the size of 3 rancher style house,like the one I was in. It had ridges all along the bottom of it, and all I could see was the bottom of the craft. I am going to say it lookes like an aircraft carrier(navy) as far as its construction and size, and I could only see the bottom. A very thin light started to shine from the bottom of the craft, and I immediately became frigtened and went back inside. I heard the hum of the craft for another 10 sec. or so, and I assume when it took leave it created a power surge, which put out the lights briefly enough for me to have to reset the clocks.I have seen other things I felt unusual, but that one was the most dramatic thing I have ever seen. It was incredible!