SOLAR SYSTEM AND RADAR — GREEN AND PETTENGILL 271 



-I 1 1 r 



T 1 1 r 



LOMMEL - 



SEELIGER 

 LAW 



O 5 10 



ECHO DELAY IN MILLISECONDS 



Figure 2. — Gordon H. Pettengill's observations of the radar brightness of the moon's disk 

 at various distances from its center are shown by dots, each representing the sum of 24,000 

 pulses. At the frequency used, 440 megacycles per second, the outer portions of the 

 moon scatter in accordance with Lambert's law, and not the Lommel-Seeliger law, which 

 fits optical measurements better. Near its center, the lunar disk is much brighter by 

 radar than Lambert's law predicts. At Stanford University, similar studies have been 

 made. 



distribution of radio energy reflected from various parts of the disk 

 would help fill remaining gaps in our understanding. If we had 

 sufficiently narrow beam widths, a radar "picture" of the moon could 

 be taken by simply scanning across its disk. However, another ap- 

 proach that does not require resolution in angle has recently shown 

 promise. 



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