The scale of the Universe is simply astounding. The best way for the layperson to understand the distances we are dealing with is not to use words like Parsecs or light years, but rather to use easy to understand analogies. Link
The image above is a photo from the Hubble telescope of the Orion Nebula. It is freely available for download from their website. The image above is the same picture at full zoom, you can see a small artifact in the middle of the picture. The picture above is a bigger resolution of the same image, this is a 18000 x 18000 pixel image (24Mb JPG), that I cropped out the section concerned.
What do you think it is? Maybe an alien mother ship, somewhere between us and the Orion Nebula. If it's several thousand kilometers away, it means that the UFO is several kilometers long.