About 30ish years ago I saw what looked like a landing light headed to the airfield (it was just on dusk), I was a pax in a car that my wife was driving. The light got bigger and brighter as it got closer, the light became a silver (chrome or mercury appearance) sphere. It was hard to tell what size the thing was, as it got even closer it went below the level of the horizon as we were in a valley/gully, you could see it against the background and appeared to be a couple of hundred feet high. The speed was hard to guess but I'd say a fast aircraft. The silver ball went passed us (guessing 200m away) and looked then to be only about a metre across, I have no real idea about distance and size. We stopped the car to watch it. The globe then looked to climb to a point about 500 feet above the airfield and appeared to hover for about 10 seconds then went straight up. The track went into a silver blur as it disapeared out of sight in what seemed like a second. The thing tracked the same direction from first sighting it till it went vertical, the direction was west. From first sight to disappearing I'd guess at 5 miles and it took about a minute maybe two at the most.
I have spent a bit of time both in the air and on the ground in the bush and remote areas, I never seen anything since like it. One of the pilots I used to work with said he had seen a very big rotating cylinder in an area that used to have a few night sightings of strange lights in the 60's and 70's.