Son of Inigo
Thinker
True story: ~snip~
Turned out it was a blimp brought in from the US for advertising, what fooled us was the trick of internally lighting the thing, gave a rather eerie glow.
That was exactly what it was for the first UFO I saw. The Metlife blimp, sans advertising (so just a 'naked' blimp skin) suddenly turning on its internal illumination, then turning it back off a couple of minutes later. The navigation lights, once the internal lights were off, were lost in the light noise of the city in the background. So this object suddenly appeared, and just as suddenly disappeared.
If it wasn't for reading about the arrival of the blimp in the paper the next morning, I would still be wondering just what it was. However, I am pretty sure I wouldn't of claimed it to extraterrestrial, just unexplained.