A celestial instrument as a memorial sun dial or star clock has a flat plate body or a spherical body that includes two hemispheres facing one another and spaced apart by a circular gap allowing sunlight to pass through the gap in the instrument. A planar date ring containing graphics surrounds the flat plate or the sphere. Upper and lower gnomons are rotatably secured to the plate or to the hemispheres. A stand includes a holder for a latitude arm that supports the gnomons. When the gap is placed in alignment with the ecliptic, sunlight can pass through a gap parallel to the plate or through a lens within the spherical body focusing a spot of light onto a display surface. A pointer on a rotatable shadow arm indicates the time on a 24-hour clock face.