Latitude of 66.5° North. The southern limit of the area of the Earth that experiences 24 hours of darkness or 24 hours of day at least one day during the year.

1550s, in reference to a celestial circle, a line around the sky which, in any location, bounds the stars which are ever-visible from that latitude (in the Northern Hemisphere, this is focused on the [..]

paralell of latitude that runs 66.5 degrees north of the Equator.

The Arctic Circle is an imaginary circle at latitude 66°30' N, around the north pole.

The circle of latitude north of which, on the solstices, every location experiences a period of continuous day or night (Lesson 29)

The parallel of latitude that is approximately 66.5 degrees north of the equator and that circumscribes the northern frigid zone.

Poleward of this latitude (66 degrees 33 minutes N) there are 24 hours of sunlight at the summer solstice and 24 hours of darkness at the winter solstice.

The parallel of latitude that runs 66° 33? 39? north of the Equator, which marks approximately the southernmost place in the Northern Hemisphere where the sun does not set on the summer solstice and [..]

Arctic Circle|lang=en