LOS ANGELES (AP) - A mysterious celestial object detected three years ago in the northern sky is baffling scientists who have been unable to figure out its makeup or how far it is from Earth. It's rare for astronomers to find an unexplainable object, but it's even more unusual for it to remain undefined for more than a week, said S. George Djorgovski, a California Institute of Technology astronomer who helped discover the object. Usually, astronomers are able to determine an object's composition and distance by breaking down its light into a spectrum and analyzing it. But the mystery object's spectrum does not fit any of the known patterns. Scientists are unsure whether the object is inside our Milky Way galaxy or at the edge of the universe.