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The lunar craters Tycho, Copernicus, and Aristarchus have been observed during lunar night at wavelengths between 3 and 14 microns. After an initial fast decrease to a color temperature of 220 degrees K, the temperature remains nearly constant through the lunar night. The data suggest that these thermal anomalies (craters) contain hot and cold regions with the hot portions constituting 2 to 10 percent of the area and probably thermally connected to a subsurface temperatuer of about 200 degrees K.

The design, calibration, and operation of the University of Minnesota's experiment on board the satellite OS0-5 are described. The instrument was designed to measure zodiacal light, airglow, and lightning. The orientation and stability of the spacecraft is also discussed as it pertains to the experiment.

Measurements over a 4-year period from the satellite OSO-5 have failed to show any temporal variations in the surface brightness and polarization of zodiacal light.

The planet Mercury was observed before, during, and after the inferior conjunctions of 29 September 1969 and 9 May 1970 at wavelengths of 3.75, 4.75, 8.6, and 12 microns. The average dark-side temperature is 111 degrees +/- 3 degrees K. The thermal inertia of the surface required to fit this temperature is close to that for the moon and indicates that Mercury and the moon have very similar top surface layers.

Analysis of the positions of nighttime thunderstorms as determined from the detection of optical radiation by satellite OSO-B reveals that ten times as many lightning storms occur over land areas as over the sea.

A comparison is made between the intensities, as measured by satellite OSO-B, of various discrete light sources on the earth (lightning, city lights, flare gas from oil wells).