Mysterious lights over city of Pittsburgh.Looked like an airplane lights flying over the city of Pittsburgh, except it kept going back and forth, as well as hovering, over a distance of several miles. Lasted a very long time. This isn't the first time I've witnessed this over the last several months. Lights appear out of nowhere, then after a good while, disappear in to thin air. Light color was white, green and red, much like the navigation lights of an aircraft. I attempted to take several photos, however, they were all blurred or too dark.