As seen from the distance of Alpha Centauri, Jupiter, at its maximum apparent separation from the sun, 3'.'94, would be a star of 23W4 (assuming that its phase function is that of Venus); it would brighten to a maximum of 22~0 at exterior conjunction. For Venus, Earth, Saturn, the maximum brightnesses and separations are, respectively: 22'~~5 and o.'55, 23~~4 and ol76, and 22~~7 and 7'l23 (with the rings at moderate inclination). Thus, a similar planetary system around Alpha Centauri would be within the reach of our largest telescopes and our current photoelectric techniques if our terrestrial atmosphere did not limit our resolution. At a separation of more than 2", it does not seem to be a serious problem to get rid of the light of the primar~ in the absence of an atmosphere. The following instrumental set tip is a possible solution: Let a 20" diaphragm, at the focal plane of a large telescope, be bisected by a highly polished razor. Let a 450 mirror on one side reflect the light into a photomultiplier and let the light on the other side go into a light trap. An~ departure from a constant signal as the position angle of the multiplier is varied would be clue to either a planetary companion or a distant star. A repetition of the experiment several months later should decide this question. Other stars from which a member of our solar system would be at least as bright as 25m0 and as far as 0'.'75 from the primary include: p NN~i, Sirius, Procyon, Altair, Fomalhaut, Vega, p Gem, and Arcturus. A telescope on ai~ artificial earth satellite can probably not provide either the size of instrument or the necessary guidance accuracy for the long periods of observing time required for this e~periment but an observatory on the moon ~ould be ideally situated. Offlcc of Space Sciences NaPonal A erono utics and Space Administration Wasltington, D. C.