I was driving on the Northwest Expressway (Interstate 795) toward Owings Mills. I moved to adjust my sun visor. When I looked up, I noticed a passenger jet going at a fast rate of speed in one direction when a much smaller wedding-cake object (round with what seemed to be two layers/levels) slowly crossed the sky going in the opposite direction. The object then came to a stop--and stayed motionless in the sky. I was driving, so I couldn't maintain visual contact. I have to say that the object was DEFINITELY different from anything I have ever seen in the sky. Please tell me that they are making weather balloons to look like wedding cakes now. I really don't want to believe that I saw a UFO.