Very large object moving silently through low clouds. (Late 1970's.)Location: Two miles east of Douglas, AZ on Geronimo Trail (road).Time/Date: Late 1970's, during the day.Some things have a big impact on your life, and this is one of those things for me, although I didn't realize it would be that at the time. I was around 10 years old. It's difficult to nail down the exact year at this point - as other than a couple years ago, I don't think I've discussed this since I moved from Douglas in the 1980's. I've thought about it many, many times, but that doesn't require nailing down a date.There's a hill out there in desert, just north of the road, where you can see the tailings from three mine shafts from the road. Just south of the road at that point is where I was standing. (There were a few exploratory mines around there, vertical, and 8-15 feet deep. They've since been filled in.) I got a young man I knew do drive me out there, as my dad wouldn't take me there as I wanted to explore the mines around there. We had just started walking south of the road when I saw it. There were very low clouds moving one way, and the clouds above it were moving a different way. It was fairly windy, and it smelled like it could rain, but it wasn't. Weather like that is uncommon (low clouds), and I was periodically looking up at the sky. There was a break in the lower clouds, and there it was. It was so large it filled the whole break. It had a dark, apparently flat bottom with features that had straight lines and gentle curves. The shape is unknown as the edges ! could not be seen. It was low in the sky, and the part that was visible appeared to be at least 2 wingspans of a 747 across. It was moving north east at a fairly slow pace, and it made no noise. The clouds were only open for about 3 seconds, and then they closed. I immediately go the attention of the man catching up behind me, and I pointed up. There was another opening a moment later, and it was there for another 3 seconds. The opening was slightly smaller, and about half of the object was part I'd just seen, and the rest was an adjacent part of its bottom. When the clouds closed the man looked at me in awe, and then did a couple double takes back to the sky. It disappeared into thicker clouds, and it would be impossible to see it again. We immediately went back to the car and headed east on Geronimo Trail, but it was hopeless. It was gone, and the road didn't go in the right direction. For weeks it was just about the only thing I talked about. We don't have any! thing nearly that big - and it was bigger than that. It moved! silentl y in a straight line in high winds, flying fairly slow and low. When I first saw it it was about 30 degrees off of being straight above me. The last view, maybe 10 seconds later, was about 45 degrees over from there. The breaks were in the lower clouds.