Very bright white, much slower that a jet

The object was longer than the jets that often fly over our property. What caught our attention was the brightness of the white and how slowly it moved. My best guess an altitude of approximately 15 to 20K feet. Attempting to photograph it, it was difficult to get focus. Even though we could see it clearly, it was not clear on the phone camera. Our best description is that of an airplane with multiple tail fins and no wings. It did not make any sound. Flights go over us at 30k feet often, but you can hear them. This was silent.