The Ghosts of Telescopes

When telescopes are used at night for stargazing, it is important that the mirrors be at the same temperature as the night sky, to avoid warm air coming off the mirrors and that air distorting the image.  So when telescopes are left on the observing field during the day, they are covered with mylar film to reflect sunlight and keep the telescopes cool.  Of course, when a whole field of telescopes have these coverings they look like ghosts, to me.