Mathematics and Society - OS X Lion Server

Our ancestors spent much time studying the motionsof the sun, moon and stars. They divided the stars ofthe night sky into groups called constellations. Onegroup of constellations, the zodiac, received specialattention.In figure 1 the solar system is placed at the centerof the celestial sphere (an imaginary large hollowsphere which appears to have the stars placed on itssurface). The twelve constellations of the zodiac liein a ring around the solar system. ("Zodiac" means"ring of animals.") The constellations of the Zodiacare listed to the right with their symbols.Although we know that the earth revolves around thesun, from earth the sun appears to move against thebackground of the stars. To help you understand theapparent motion of the sun, have a friend who representsthe sun stand in the middle of a room. As you walkslowly around the person, observe how the person appearsto move around against the background of the room.Similarly the sun appears to wander among the con-stellations of the zodiac. The apparentamong the stars is called the ecliptic.ferent times of the year the sun will appear to be indifferent constellations of the zodiac.THEZODIACFIGURE 1Constellations of the ZodiacAries (the ram)crTaurus (the bull) ~Gemini (the twins) 11Cancer (the crab) 69Leo (the lion)Virgo (the virgin)Libra (the scales)cf\.W:::C::l1\.,Scorpius (the scorpion)Sagittarius (the archer);£!Capricornus (the goat) VfAquarius (the waterI!WI/V\IINbearer)Pisces (the fish)*@LEOTAURUSA ~.GEMlt.J1C.A.OCER.0SUI\)•EARTHARIES'\,FIGURE: 2.E.CLIPTIC~CORPIUS• •path of the sunThus at dif--"'-SA(:.ITTARIU$CAPR.ICOR~U'?>GRAPH Ie FROM:Modern Space Science, by F. E. Trinklein and C. M. Huffer,Copyright© 1961, Holt, Rinehart and Winston, Publishers.Permission to use granted by Holt, Rinehart and Winston, Publishers 117