1/cd-hl ./.-hl Introduction/nn-hl It/pps has/hvz recently/rb become/vbn practical/jj to/to use/vb the/at radio/nn emission/nn of/in the/at moon/nn and/cc planets/nns as/cs a/at new/jj source/nn of/in information/nn about/in these/dts bodies/nns and/cc their/pp$ atmospheres/nns ./. The/at results/nns of/in present/jj observations/nns of/in the/at thermal/jj radio/nn emission/nn of/in the/at moon/nn are/ber consistent/jj with/in the/at very/ql low/jj thermal/jj conductivity/nn of/in the/at surface/nn layer/nn which/wdt was/bedz derived/vbn from/in the/at variation/nn in/in the/at infrared/jj emission/nn during/in eclipses/nns (/( e.g./rb ,/, Garstung/np ,/, 1958/cd )/) ./. When/wrb sufficiently/ql accurate/jj and/cc complete/jj measurements/nns are/ber available/jj ,/, it/pps will/md be/be possible/jj to/to set/vb limits/nns on/in the/at thermal/jj and/cc electrical/jj characteristics/nns of/in the/at surface/jj and/cc subsurface/jj materials/nns of/in the/at moon/nn ./. Observations/nns of/in the/at radio/nn emission/nn of/in a/at planet/nn which/wdt has/hvz an/at extensive/jj atmosphere/nn will/md probe/vb the/at atmosphere/nn to/in a/at greater/jjr extent/nn than/cs those/dts using/vbg shorter/jjr wave/nn lengths/nns and/cc should/md in/in some/dti cases/nns give/vb otherwise/rb unobtainable/jj information/nn about/in the/at characteristics/nns of/in the/at solid/jj surface/nn ./. Radio/nn observations/nns of/in Venus/np and/cc Jupiter/np have/hv already/rb supplied/vbn unexpected/jj experimental/jj data/nn on/in the/at physical/jj conditions/nns of/in these/dts planets/nns ./. The/at observed/vbn intensity/nn of/in the/at radio/nn emission/nn of/in Venus/np is/bez much/ql higher/jjr than/cs the/at expected/vbn thermal/jj intensity/nn ,/, although/cs the/at spectrum/nn indicated/vbn by/in measurements/nns at/in wave/nn lengths/nns near/in 3/cd cm/nn and/cc 10/cd cm/nn is/bez like/cs that/dt of/in a/at black/jj body/nn at/in about/rb 600-degrees/nns ./. This/dt result/nn suggests/vbz a/at very/ql high/jj temperature/nn at/in the/at solid/jj surface/nn of/in the/at planet/nn ,/, although/cs there/ex is/bez the/at possibility/nn that/cs the/at observed/vbn radiation/nn may/md be/be a/at combination/nn of/in both/abx thermal/jj and/cc non-thermal/jj components/nns and/cc that/cs the/at observed/vbn spectrum/nn is/bez that/dt of/in a/at black/jj body/nn merely/rb by/in coincidence/nn ./. For/in the/at case/nn of/in Jupiter/np ,/, the/at radio/nn emission/nn spectrum/nn is/bez definitely/rb not/* like/cs the/at spectrum/nn of/in a/at black-body/nn radiator/nn ,/, and/cc it/pps seems/vbz very/ql likely/jj that/cs the/at radiation/nn reaching/vbg the/at earth/nn is/bez a/at combination/nn of/in thermal/jj radiation/nn from/in the/at atmosphere/nn and/cc non-thermal/jj components/nns ./. Of/in the/at remaining/vbg planets/nns ,/, only/ap Mars/np and/cc Saturn/np have/hv been/ben observed/vbn as/cs radio/nn sources/nns ,/, and/cc not/* very/ql much/ap information/nn is/bez available/jj ./. Mars/np has/hvz been/ben observed/vbn twice/rb at/in about/rb 3-cm/nn wave/nn length/nn ,/, and/cc the/at intensity/nn of/in the/at observed/vbn radiation/nn is/bez in/in reasonable/jj agreement/nn with/in the/at thermal/jj radiation/nn which/wdt might/md be/be predicted/vbn on/in the/at basis/nn of/in the/at known/vbn temperature/nn of/in Mars/np ./. The/at low/jj intensity/nn of/in the/at radiation/nn from/in Saturn/np has/hvz limited/vbn observations/nns ,/, but/cc again/rb the/at measured/vbn radiation/nn seems/vbz to/to be/be consistent/jj with/in a/at thermal/jj origin/nn ./. No/at attempts/nns to/to measure/vb the/at radio/nn emission/nn of/in the/at remaining/vbg planets/nns have/hv been/ben reported/vbn ,/, and/cc ,/, because/rb of/in their/pp$ distances/nns ,/, small/jj diameters/nns ,/, or/cc low/jj temperatures/nns ,/, the/at thermal/jj radiation/nn at/in radio/nn wave/nn lengths/nns reaching/vbg the/at earth/nn from/in these/dts sources/nns is/bez expected/vbn to/to be/be of/in very/ql low/jj intensity/nn ./. In/in spite/nn of/in this/dt ,/, the/at very/ql large/jj radio/nn reflectors/nns and/cc improved/vbn amplifying/vbg techniques/nns which/wdt are/ber now/rb becoming/vbg available/jj should/md make/vb it/ppo possible/jj to/to observe/vb the/at radio/nn emission/nn of/in most/ap of/in the/at planets/nns in/in a/at few/ap years/nns ./. The/at study/nn of/in the/at radio/nn emission/nn of/in the/at moon/nn and/cc planets/nns began/vbd with/in the/at detection/nn of/in the/at thermal/jj radiation/nn of/in the/at moon/nn at/in 1.25-cm/nn wave/nn length/nn by/in Dicke/np and/cc Beringer/np (/( 1946/cd )/) ./. This/dt was/bedz followed/vbn by/in a/at comprehensive/jj series/nn of/in observations/nns of/in the/at 1.25-cm/nn emission/nn of/in the/at moon/nn over/in three/cd lunar/jj cycles/nns by/in Piddington/np and/cc Minnett/np (/( 1949/cd )/) ./. They/ppss deduced/vbd from/in their/pp$ measurements/nns that/cs the/at radio/nn emission/nn from/in the/at whole/jj disk/nn of/in the/at moon/nn varied/vbd during/in a/at lunation/nn in/in a/at roughly/ql sinusoidal/jj fashion/nn ;/. ;/. that/cs the/at amplitude/nn of/in the/at variation/nn was/bedz considerably/ql less/ap than/cs the/at amplitude/nn of/in the/at variation/nn in/in the/at infrared/jj emission/nn as/cs measured/vbn by/in Pettit/np and/cc Nicholson/np (/( 1930/cd )/) and/cc Pettit/np (/( 1935/cd )/) ;/. ;/. and/cc that/cs the/at maximum/nn of/in the/at radio/nn emission/nn came/vbd about/rb 3-1/2/cd days/nns after/in Full/jj-tl Moon/nn-tl ,/, which/wdt is/bez again/rb in/in contrast/nn to/in the/at infrared/jj emission/nn ,/, which/wdt reaches/vbz its/pp$ maximum/nn at/in Full/jj-tl Moon/nn-tl ./. Piddington/np and/cc Minnett/np explained/vbd their/pp$ observations/nns by/in pointing/vbg out/rp that/cs rocklike/jj materials/nns which/wdt are/ber likely/jj to/to make/vb up/rp the/at surface/nn of/in the/at moon/nn would/md be/be partially/ql transparent/jj to/in radio/nn waves/nns ,/, although/cs opaque/jj to/in infrared/jj radiation/nn ./. The/at infrared/jj emission/nn could/md then/rb be/be assumed/vbn to/to originate/vb at/in the/at surface/nn of/in the/at moon/nn ,/, while/cs the/at radio/nn emission/nn originates/vbz at/in some/dti depth/nn beneath/in the/at surface/nn ,/, where/wrb the/at temperature/nn variation/nn due/jj to/in solar/jj radiation/nn is/bez reduced/vbn in/in amplitude/nn and/cc shifted/vbn in/in phase/nn ./. Since/cs the/at absorption/nn of/in radio/nn waves/nns in/in rocklike/jj material/nn varies/vbz with/in wave/nn length/nn ,/, it/pps should/md be/be possible/jj to/to sample/vb the/at temperature/nn variation/nn at/in different/jj depths/nns beneath/in the/at surface/nn and/cc possibly/rb detect/vb changes/nns in/in the/at structure/nn or/cc composition/nn of/in the/at lunar/jj surface/nn material/nn ./. The/at radio/nn emission/nn of/in a/at planet/nn was/bedz first/rb detected/vbn in/in 1955/cd ,/, when/wrb Burke/np and/cc Franklin/np (/( 1955/cd )/) identified/vbn the/at origin/nn of/in interference-like/jj radio/nn noise/nn on/in their/pp$ records/nns at/in about/rb 15/cd meters/nns wave/nn length/nn as/cs emission/nn from/in Jupiter/np ./. This/dt sporadic/jj type/nn of/in planetary/jj radiation/nn is/bez discussed/vbn by/in Burke/np (/( chap./nn 13/cd )/) and/cc Gallet/np (/( chap./nn 14/cd )/) ./. Steady/jj radiation/nn which/wdt was/bedz presumably/rb of/in thermal/jj origin/nn was/bedz observed/vbn from/in Venus/np at/in 3.15/cd and/cc 9.4/cd cm/nn ,/, and/cc from/in Mars/np and/cc Jupiter/np at/in 3.15/cd cm/nn in/in 1956/cd (/( Mayer/np ,/, McCullough/np ,/, and/cc Sloanaker/np ,/, 1958/cd ,/, A/np ,/, B/np ,/, C/np )/) ,/, and/cc from/in Saturn/np at/in 3.75/cd cm/nn in/in 1957/cd (/( Drake/np and/cc Ewen/np ,/, 1958/cd )/) ./. In/in the/at relatively/ql short/jj time/nn since/in these/dts early/jj observations/nns ,/, Venus/np has/hvz been/ben observed/vbn at/in additional/jj wave/nn lengths/nns in/in the/at range/nn from/in 0.8/cd to/in 10.2/cd cm/nn ,/, and/cc Jupiter/np has/hvz been/ben observed/vbn over/in the/at wave-length/nn range/nn from/in 3.03/cd to/in 68/cd Aj/nn ./. The/at observable/jj characteristics/nns of/in planetary/jj radio/nn radiation/nn are/ber the/at intensity/nn ,/, the/at polarization/nn ,/, and/cc the/at direction/nn of/in arrival/nn of/in the/at waves/nns ./. The/at maximum/jj angular/jj diameter/nn of/in any/dti planetary/jj disk/nn as/cs observed/vbn from/in the/at earth/nn is/bez about/rb 1/cd minute/nn of/in arc/nn ./. This/dt is/bez much/ql smaller/jjr than/cs the/at highest/jjt resolution/nn of/in even/rb the/at very/ql large/jj reflectors/nns now/rb under/in construction/nn ,/, and/cc consequently/rb the/at radio/nn emission/nn of/in different/jj regions/nns of/in the/at disk/nn cannot/md* be/be resolved/vbn ./. It/pps should/md be/be possible/jj ,/, however/rb ,/, to/to put/vb useful/jj limits/nns on/in the/at diameters/nns of/in the/at radio/nn sources/nns by/in observing/vbg with/in large/jj reflectors/nns or/cc with/in interferometers/nns ./. Measurements/nns of/in polarization/nn are/ber presently/rb limited/vbn by/in apparatus/nn sensitivity/nn and/cc will/md remain/vb difficult/jj because/rb of/in the/at low/jj intensity/nn of/in the/at planetary/jj radiation/nn at/in the/at earth/nn ./. There/ex have/hv been/ben few/ap measurements/nns specifically/rb for/in the/at determination/nn of/in the/at polarization/nn of/in planetary/jj radiation/nn ./. The/at measurements/nns made/vbn with/in the/at NRL/nn 50-foot/jj reflector/nn ,/, which/wdt is/bez altitude-azimuth-mounted/jj ,/, would/md have/hv shown/vbn a/at systematic/jj change/nn with/in local/jj hour/nn angle/nn in/in the/at measured/vbn intensities/nns of/in Venus/np and/cc Jupiter/np if/cs a/at substantial/jj part/nn of/in the/at radiation/nn had/hvd been/ben linearly/rb polarized/vbn ./. Recent/jj interferometer/nn measurements/nns (/( Radhakrishnan/np and/cc Roberts/np ,/, 1960/cd )/) have/hv shown/vbn the/at 960-mc/nn emission/nn of/in Jupiter/np to/to be/be partially/rb polarized/vbn and/cc to/to originate/vb in/in a/at region/nn of/in larger/jjr diameter/nn than/cs the/at visible/jj disk/nn ./. Other/ap than/cs this/dt very/ql significant/jj result/nn ,/, most/ap of/in the/at information/nn now/rb available/jj about/in the/at radio/nn emission/nn of/in the/at planets/nns is/bez restricted/vbn to/in the/at intensity/nn of/in the/at radiation/nn ./. The/at concept/nn of/in apparent/jj black-body/nn temperature/nn is/bez used/vbn to/to describe/vb the/at radiation/nn received/vbn from/in the/at moon/nn and/cc the/at planets/nns ./. The/at received/vbn radiation/nn is/bez compared/vbn with/in the/at radiation/nn from/in a/at hypothetical/jj black/jj body/nn which/wdt subtends/vbz the/at same/ap solid/jj angle/nn as/cs the/at visible/jj disk/nn of/in the/at planet/nn ./. The/at apparent/jj black-body/nn disk/nn temperature/nn is/bez the/at temperature/nn which/wdt must/md be/be assumed/vbn for/in the/at black/jj body/nn in/in order/nn that/cs the/at intensity/nn of/in its/pp$ radiation/nn should/md equal/vb that/dt of/in the/at observed/vbn radiation/nn ./. The/at use/nn of/in this/dt concept/nn does/doz not/* specify/vb the/at origin/nn of/in the/at radiation/nn ,/, and/cc only/rb if/cs the/at planet/nn really/rb radiates/vbz as/cs a/at black/jj body/nn ,/, will/md the/at apparent/jj black-body/nn temperature/nn correspond/vb to/in the/at physical/jj temperature/nn of/in the/at emitting/vbg material/nn ./. The/at radio/nn radiation/nn of/in the/at sun/nn which/wdt is/bez reflected/vbn from/in the/at moon/nn and/cc planets/nns should/md be/be negligible/jj compared/vbn with/in their/pp$ thermal/jj emission/nn at/in centimeter/nn wave/nn lengths/nns ,/, except/in possibly/rb at/in times/nns of/in exceptional/jj outbursts/nns of/in solar/jj radio/nn noise/nn ./. The/at quiescent/jj level/nn of/in centimeter/nn wave-length/nn solar/jj radiation/nn would/md increase/vb the/at average/jj disk/nn brightness/nn temperature/nn by/in less/ap than/in 1-degree/nn ./. At/in meter/nn wave/nn lengths/nns an/at increase/nn of/in the/at order/nn of/in 10-degrees/nns in/in the/at average/jj disk/nn temperatures/nns of/in the/at nearer/jjr planets/nns would/md be/be expected/vbn ./. Therefore/rb ,/, neglecting/vbg the/at extreme/jj outbursts/nns ,/, reflected/vbn solar/jj radiation/nn is/bez not/* expected/vbn to/to cause/vb sizable/jj errors/nns in/in the/at measurements/nns of/in planetary/jj radiation/nn in/in the/at centimeter-/nn and/cc decimeter-wave-length/nn range/nn ./. 2/cd-hl ./.-hl The/at-hl moon/nn-hl 2.1/cd-hl observations/nns-hl Radio/nn observations/nns of/in the/at moon/nn have/hv been/ben made/vbn over/in the/at range/nn of/in wave/nn lengths/nns from/in 4.3/cd mm/nn to/in 75/cd cm/nn ,/, and/cc the/at results/nns are/ber summarized/vbn in/in Table/nn-tl 1/cd-tl ./. Observations/nns have/hv also/rb been/ben made/vbn at/in 1.5/cd mm/nn using/vbg optical/jj techniques/nns (/( Sinton/np ,/, 1955/cd ,/, 1956/cd ,/, ;/. ;/. see/vb also/rb chap./nn 11/cd )/) ./. Not/* all/abn the/at observers/nns have/hv used/vbn the/at same/ap procedures/nns or/cc made/vbn the/at same/ap assumptions/nns about/in the/at lunar/jj brightness/nn distribution/nn when/wrb reducing/vbg the/at data/nn ,/, and/cc this/dt ,/, together/rb with/in differences/nns in/in the/at methods/nns of/in calibrating/vbg the/at antennae/nns and/cc receivers/nns ,/, must/md account/vb for/in much/ap of/in the/at disagreement/nn in/in the/at measured/vbn radio/nn brightness/nn temperatures/nns ./. In/in the/at observations/nns at/in 4.3/cd mm/nn (/( Coates/np ,/, 1959/cd )/) ,/, the/at diameter/nn of/in the/at antenna/nn beam/nn ,/, 6'.7/nn ,/, was/bedz small/jj enough/qlp to/to allow/vb resolution/nn of/in some/dti of/in the/at larger/jjr features/nns of/in the/at lunar/jj surface/nn ,/, and/cc contour/nn diagrams/nns have/hv been/ben made/vbn of/in the/at lunar/jj brightness/nn distribution/nn at/in three/cd lunar/jj phases/nns ./. These/dts observations/nns indicate/vb that/cs the/at lunar/jj maria/fw-nns heat/vb up/rp more/ql rapidly/rb and/cc also/rb cool/vb off/rp more/ql rapidly/rb than/cs do/do the/at mountainous/jj regions/nns ./. Mare/fw-nn-tl Imbrium/np-tl seems/vbz to/to be/be an/at exception/nn and/cc remains/vbz cooler/jjr than/cs the/at regions/nns which/wdt surround/vb it/ppo ./. These/dts contour/nn diagrams/nns also/rb suggest/vb a/at rather/ql rapid/jj falloff/nn in/in the/at radio/nn brightness/nn with/in latitude/nn ./. Very/ql recently/rb ,/, observations/nns have/hv been/ben made/vbn at/in 8-mm/nn wave/nn length/nn with/in a/at reflector/nn 22/cd meters/nns in/in diameter/nn with/in a/at resultant/jj beam/nn width/nn of/in only/rb about/rb 2'/nns (/( Amenitskii/np ,/, Noskova/np ,/, and/cc Salomonovich/np ,/, 1960/cd )/) ./. The/at constant-temperature/nn contours/nns are/ber much/ql smoother/jjr than/cs those/dts observed/vbn at/in 4.3/cd mm/nn by/in Coates/np (/( 1959/cd )/) and/cc apparently/rb the/at emission/nn at/in 8/cd mm/nn is/bez not/* nearly/rb so/ql sensitive/jj to/in differences/nns in/in surface/jj features/nns ./. Such/jj high-resolution/nn observations/nns as/cs these/dts are/ber needed/vbn at/in several/ap wave/nn lengths/nns in/in order/nn that/cs the/at radio/nn emission/nn of/in the/at moon/nn can/md be/be properly/rb interpreted/vbn ./. The/at observations/nns of/in Mayer/np ,/, McCullough/np ,/, and/cc Sloanaker/np at/in 3.15/cd cm/nn and/cc of/in Sloanaker/np at/in 10.3/cd cm/nn have/hv not/* previously/rb been/ben published/vbn and/cc will/md be/be briefly/rb described/vbn ./. Measurements/nns at/in 3.15/cd cm/nn were/bed obtained/vbn on/in 11/cd days/nns spread/vbn over/in the/at interval/nn May/np 3/cd to/in June/np 19/cd ,/, 1956/cd ,/, using/vbg the/at 50-foot/jj reflector/nn at/in the/at U./np-tl S./np-tl Naval/jj-tl Research/nn-tl Laboratory/nn-tl in/in Washington/np ./. The/at half-intensity/nn diameter/nn of/in the/at antenna/nn beam/nn was/bedz about/rb 9'/nns ,/, and/cc the/at angle/nn subtended/vbn by/in the/at moon/nn included/vbd the/at entire/jj main/jjs beam/nn and/cc part/nn of/in the/at first/od side/jj lobes/nns ./. The/at antenna/nn patterns/nns and/cc the/at power/nn gain/nn at/in the/at peak/nn of/in the/at beam/nn were/bed both/abx measured/vbn (/( Mayer/np ,/, McCullough/np ,/, and/cc Sloanaker/np ,/, 1958/cd )/) ,/, so/cs that/cs the/at absolute/jj power/nn sensitivity/nn of/in the/at antenna/nn beam/nn over/in the/at solid/jj angle/nn of/in the/at moon/nn was/bedz known/vbn ./. The/at ratio/nn of/in the/at measured/vbn antenna/nn temperature/nn change/nn during/in a/at drift/nn scan/nn across/in the/at moon/nn to/in the/at average/jj brightness/nn temperature/nn of/in the/at moon/nn over/in the/at antenna/nn beam/nn (/( assuming/vbg that/cs the/at brightness/nn temperature/nn of/in the/at sky/nn is/bez negligible/jj )/) was/bedz found/vbn ,/, by/in graphical/jj integration/nn of/in the/at antenna/nn directivity/nn diagram/nn ,/, to/to be/be 0.85/cd ./. The/at measured/vbn brightness/nn temperature/nn is/bez a/at good/jj approximation/nn to/in the/at brightness/nn temperature/nn at/in the/at center/nn of/in the/at lunar/jj disk/nn because/rb of/in the/at narrow/jj antenna/nn beam/nn and/cc because/cs the/at temperature/nn distribution/nn over/in the/at central/jj portion/nn of/in the/at moon's/nn$ disk/nn is/bez nearly/ql uniform/jj ./. The/at result/nn of/in the/at observations/nns is/bez Af/nn where/wrb the/at phase/nn angle/nn ,/, Q/np ,/, is/bez measured/vbn in/in degrees/nns from/in new/jj moon/nn and/cc the/at probable/jj errors/nns include/vb absolute/jj as/ql well/rb as/cs relative/jj errors/nns ./. This/dt result/nn is/bez plotted/vbn along/rb with/in the/at 8.6-mm/nn observations/nns of/in Gibson/np (/( 1958/cd )/) in/in figure/nn 1/cd ,/, A/np ./. The/at variation/nn in/in the/at 3-cm/nn emission/nn of/in the/at moon/nn during/in a/at lunation/nn is/bez very/ql much/ql less/ap than/cs the/at variation/nn in/in the/at 8.6-mm/nn emission/nn ,/, as/cs would/md be/be expected/vbn from/in the/at explanation/nn of/in Piddington/np and/cc Minnett/np (/( 1949/cd )/) ./. In/in the/at discussion/nn which/wdt follows/vbz ,/, the/at time/nn average/nn of/in the/at radio/nn emission/nn will/md be/be referred/vbn to/in as/cs the/at constant/jj component/nn ,/, and/cc the/at superimposed/vbn periodic/jj variation/nn will/md be/be called/vbn the/at variable/jj component/nn ./. The/at 10.3-cm/nn observation/nn of/in Sloanaker/np was/bedz made/vbn on/in May/np 20/cd ,/, 1958/cd ,/, using/vbg the/at 84-foot/nn reflector/nn at/in the/at Maryland/np-tl Point/nn-tl Observatory/nn-tl of/in the/at U./np-tl S./np-tl Naval/jj-tl Research/nn-tl Laboratory/nn-tl ./. The/at age/nn of/in the/at moon/nn was/bedz about/rb 2/cd days/nns ./. The/at half-intensity/nn diameter/nn of/in the/at main/jjs lobe/nn of/in the/at antenna/nn was/bedz about/rb 18'.5/nns ,/, and/cc the/at brightness/nn temperature/nn was/bedz reduced/vbn by/in assuming/vbg a/at Gaussian/jj shape/nn for/in the/at antenna/nn beam/nn and/cc a/at uniformly/rb bright/jj disk/nn for/in the/at moon/nn ./.