PURE SCIENCE 
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523.2 
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2. 
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“A 
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Solar system 
Distributiv laws of planets 
Conjunctions and oppositions 
Motion of solar system in space 
Constitution of planetary system 
Stability of solar system Ecliptic 
Orrery, planetarium, gyroscope, ete. 
See 531.34 Rotation 
Zodiac 
Moon 
Constants: size, mass Distance and parallax 
Heat and light Phases 
Orbit and motions 
Sidereal month, tropical, perigee and apogee, sun and earth’s attraction, 
librations. See also 521.6 for Orbit 
Features of surface: mountains, plains, etc. 
Atmosphere 
Physical condition 
Spectrum 
Eclipses 
Charts, photografs, etc. 
Planets 
Mercury and intramercurial 
Venus 
Mars 
Asteroids 
Jupiter 
Saturn 
Uranus 
Neptune and transneptunian 
Charts, photografs, etc. 
Meteors and zodiacal light 
Meteorites 
Fireballs 
Meteoric showers, radiant points, etc. 
Svstems of meteors 
Connection of comets and meteors 
Spectrum 
Hight of atmosphere from observation 
Zodiacal light Aurora (borealis and australis)