1) Head of the world 2) High-latitude formation 3) Ice mass way up north 4) Inuit headgear 5) Source of some icebergs 
Icy region of a planet, specifically the north and south pole.
(from the article `Mars`) For telescopic observers, the most striking regular changes on Mars occur at the poles. With the onset of fall in a particular hemisphere, clouds ... The polar caps...and are caused by bombardment of the atmosphere by energetic charged particles. On the dayside, magnetic field lines from high latitudes split, ....
polar region bounded by an auroral zone