 The planetarium projector was a 13 @-@ foot ( 4 @.@ 0 m ) -long dumbbell @-@ shaped object , with 29 @-@ inch ( 740 mm ) -diameter spheres attached at each end representing the night sky for the northern and southern hemispheres . Connecting the two spheres was a framework that held nearly 150 individual projectors , including those dedicated to the planets , the Sun , and specific stars . 
