Arctic Circle

The sun on the Arctic Circle

How to use it

1. The line is drawn in orange across the whole map as soon as the page opens.
2. Pan and zoom to follow it. On the web map's Mercator projection, parallels are straight horizontal lines and meridians straight vertical ones.
3. Under the map, read the list of countries whose land the line crosses and the notes about the line.
4. Use the other line pages linked below to compare positions, or the miles per degree calculator for the length of a degree at this latitude.

Why the Arctic Circle is where it is

The Arctic Circle marks the southern edge of the region where the sun can stay above the horizon for a full day in summer and below it for a full day in winter. Its latitude is 90° minus the axial tilt, which with the J2000 value is 66.5606° N.

On the geometric definition the midnight sun would just touch the horizon on the circle at the June solstice. Refraction lifts the sun by about half a degree near the horizon, so in practice the midnight sun can be seen a little south of the line, and polar night begins a little north of it.

How long the line is

A parallel is a circle whose radius is the distance from the Earth's axis. On the WGS84 ellipsoid that radius is N · cos φ, where N is the prime vertical radius of curvature, which at 66.5606° N is 6,396,184 m. The circumference 2π · N · cos φ comes to 15,986.1 km.

One degree of longitude along it is 44.41 km, or 27.59 miles. The miles per degree calculator gives the same figure for any latitude.

Countries on the line

Testing a point every 0.02° along the line against the Natural Earth 1:50m outlines finds land in 7 countries: Norway, Sweden, Finland, Russia, United States, Canada, Denmark. At that scale small islands drop out, so the list covers the mainland and larger islands.

• Denmark is listed for Greenland.
• Iceland's mainland lies south of the circle. Its small northern island of Grímsey is too small to show at the 1:50m scale.

The United States and this line

Alaska is the only US state crossed by the Arctic Circle. Juneau, the capital, lies at 58.301° N, which is 572 miles south of the circle along a meridian. On the June solstice Juneau still gets 18.3 hours of daylight.