Observations of the solar diameter and shape are of considerable interest for astrophysicists dealing with the interior structure, rotation, pulsations and evolution of stars. Also there has been considerable interest in longterm variations in the solar output and diameter as it relates to climatic variations. The paper describes an experiment which holds promise for accomplishing these observations with very high precision over a long period of time. With it, it might even be possible to detect the gradual evolutionary change of the Sun within decades. More rapid changes related, for example, to climatic variations on Earth would be detectable in a short time. The experiment has a component both in space and on Earth. The space component consists of a flat reflector 1–2 m in diameter in geostationary orbit. It acts as a reflecting pin-hole telescope forming an image of the Sun on the Earth 350 km in diameter. The earth component consists of the machinery needed to measure this image. This paper elaborates on these concepts and defines problem areas which need further studies.