section_path: Definition and etymology
section_name: Definition and etymology
paragraph_text: Definition and etymology
  
  The word Arctic comes from the Greek word ἀρκτικός (arktikos), "near the Bear, northern" and from the word ἄρκτος (arktos), meaning bear. The name refers either to the constellation known as Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere, or to the constellation Ursa Minor, the "Little Bear", which contains the celestial north pole (currently very near Polaris, the current north Pole Star, or North Star).
  
  There are a number of definitions of what area is contained within the Arctic. The area can be defined as north of the Arctic Circle (about 66° 34'N), the approximate southern limit of the midnight sun and the polar night. Another definition of the Arctic, which is popular with ecologists, is the region in the Northern Hemisphere where the average temperature for the warmest month (July) is below 10 °C (50 °F); the northernmost tree line roughly follows the isotherm at the boundary of this region.