Observed large craft with solid red light in the center and a large bright white strobe on either side. hovered south of rincon mountains for approximately 15 minutes. observed craft through binoculars. object appeared to be at approximately 20,000 ft. strobes stopped flashing and the object began moving nw as a solid red orb. object passed overhead and no sound was observed. the red orb gained altitude and speed at an unusually high rate until it had disappeared from view to the nw. there were slight abrupt directional changes to the north and south as it moved away. no other air traffic was observed during the entire duration of the sighting, which is unusual for the area.