Lighted object traveling north bound at a high elevation and at a high rate of speed curved to the Northeast

While driving north bound on La Cholla Blvd. in Oro Valley, AZ I noticed a bright light in the sky ahead of me moving slowly. Suddenly, a smaller and more dimly lit object came from the Southwest towards the brightly lit object. At first, I thought it was a fast-moving jet on an intercept course with the bright object, which I eventually recognized as a plane or helicopter, but the dimly lit object (UFO) passed by the first object and kept moving to the north at an extremely high rate of speed. The UFO was traveling so fast that it literally went from somewhere over my head to the horizon in a matter of about 10 seconds. As the UFO approached the horizon to the north, it arced towards the northeast and disappeared over the horizon. I was in the process of taking a picture of the brightly lit plane or helicopter when the UFO appeared. I took a picture, but only the lights of the two objects can be seen with no detail other than the amount of light they were emitting.