Around 9:00 or 10:00, i have noticed high flying aircraft next to the plane a dim like dot or sphere moved away from large aircraft it match the aircraft speed until it just vanished. I know plane was much higher than commerical air traffic and dot or sphere was following or moving parting. Matching speed until just vanished. Direction was coming from south and disapeared from plain sight and not horizon sight, but nearly straight up perfect clear view ablsoltly no explaining how it just vanished no sound from dot/shpere but eventully heard the large aircraft later becuase of its distance and alltutide. Dot/sphere was in full view about 3 minutes and just gone large plane did not change speed or directipn and was completly visible until it was over the horizon or field or view witch was 10 to 15 minutes straight north.