▁the ▁North - Z en ith - S outh ▁plane ▁is ▁offset , ▁with ▁" effect ive " ▁North ▁actually ▁located ▁somewhat ▁toward ▁the ▁West . ▁Thus ▁if ▁the ▁sun ▁sets ▁at ▁an ▁az im uth ▁of ▁ 2 5 5 ° ▁( 1 5 ° ▁South ▁of ▁West ) ▁the ▁polar ization ▁pattern ▁will ▁be ▁at ▁its ▁maximum ▁along ▁the ▁horizon ▁at ▁an ▁az im uth ▁of ▁ 3 4 5 ° ▁( 1 5 ° ▁West ▁of ▁North ) ▁and ▁ 1 6 5 ° ▁( 1 5 ° ▁East ▁of ▁South ). ▁ ▁During ▁a ▁single ▁day , ▁the ▁pattern ▁rot ates ▁with ▁the ▁changing ▁position ▁of ▁the ▁sun . ▁ ▁At ▁tw il ight ▁it ▁typically ▁appears ▁about ▁ 4 5 ▁minutes ▁before ▁local ▁sun r ise ▁and ▁disapp ears ▁ 4 5 ▁minutes ▁after ▁local ▁sun set . ▁Once ▁established ▁it ▁is ▁very ▁stable , ▁showing ▁change ▁only ▁in ▁its ▁rotation . ▁It ▁can ▁easily ▁be ▁seen ▁on ▁any ▁given ▁day ▁using ▁polar ized ▁s ung lass es . ▁ ▁Many ▁animals ▁use ▁the ▁polar ization ▁patterns ▁of ▁the ▁sky ▁at ▁tw il ight ▁and ▁throughout ▁the ▁day ▁as ▁a ▁navigation ▁tool . ▁ ▁Because ▁it ▁is ▁determined ▁purely ▁by ▁the ▁position ▁of ▁the ▁sun , ▁it ▁is ▁easily ▁used ▁as ▁a ▁comp ass ▁for ▁animal ▁orientation . ▁ ▁By ▁orient ing ▁themselves ▁with ▁respect ▁to ▁the ▁polar ization ▁patterns , ▁animals ▁can ▁locate ▁the ▁sun ▁and ▁thus ▁determine ▁the ▁cardinal ▁directions . ▁ ▁Theory ▁ ▁Ge ometry