The first observations of the planets at 20IL were reported by Low (Lowell Obs. Bull. 128, 184, 1965). Using the same radiometer, which cuts on at 17.5 IL and is uniformly sensitive to about 25 IL' further observations have been made with angular resolutions between 4 and 35 arcsec. Under the assumption that Mars radiates as a blackbody, its brightness temperature at 20IL was taken as 2250*5 0K, the value measured for the disk at 10IL This yielded a temperature for Venus at 20IL of 248*100K, significantly above the 10~IL value of 221*100K but in good agreement with solar heating. Using Mars and Venus as standards, it was possible to observe Saturn with angular resolutions both large and small compared to its disk. Correcting for the obscuration of the rings, which were found to be much colder than the planet, the mean disk brightness temperature was 95 ~ 30 K, quite close to the measured value of 930 K at 10~ (Low, F. J., Astron. J. 69, 550, 1964). Scans of Jupiter show a hot equatorial band, 150*5 0K, covering about half the disk; the poles are about 1300 K. Although the equatorial scans show significant limb darkening, the east and west limbs are equal in temperature to within the accuracy of measurement. The total amount of energy Jupiter receives from the sun is less than the observed radiation between 10 and 25 IL and would produce an effective temperature of only 1050 K. Thus an internal supply of energy must be present. The Jovian temperature measured at 1 mm is 155*150K (Low, F. J., and Davidson, A. W., Astrophys. J. 142, 1278, 1965). If the brightness temperature between 25 IL and 1 mm does not drop below 1400 K, the total power radiated by Jupiter is more than 3 times the insolation. A similar conclusion may be drawn for Saturn; however, since only a small fraction of its total energy is observed, its excess brightness temperature at 20 IL may be caused by a greenhouse effect.