I was outside on front porch, I heard a deep hum but didn't notice any sound until I saw an object move in the sky. I thought it was a dark plane but I saw no blinking lights. It seemed to have several round shapes on bottom which could have been for lights or it reflected from city lights (not sure because it looked lighter then the object but dark enough you didn't notice. It moved very fast south and disappeared from my view. I still heard a deep hum for maybe two seconds after it disappeared.