Category Earth Science

The Arctic Circle is a line of latitude that circles the Earth at approximately 66° 33′ 47.2″ north of the Equator. How was that strange number determined? The position of the Arctic Circle is at the latitude above which the sun does not set on the summer solstice and does not rise on the winter solstice.

This is what causes the Arctic to have a very long continuous night each year and a very long continuous day. The length of these long continuous days and nights are six months each at the North Pole. Their length decreases with distance from the North Pole.

The latitude of the Arctic Circle is slowly drifting northward at a speed of about 15 meters per year. On July 2, 2018 it was at approximately 66° 33′ 47.2″ north of the Equator. This drift has nothing to do with climate change. Instead, the drift occurs because the Earth wobbles on its axis of rotation in a 40,000 year cycle in response to the gravitational attraction of the moon.

To most of the general public, using the Arctic Circle as the defining southern boundary for “the Arctic” is easy and makes total sense. However, some researchers believe that there are better ways to draw a map of the Arctic.

Credit: geology.com

Picture credit: Google

The Earth’s Equator is the imaginary line that runs around the centre of the globe at 0 degrees latitude, at equal distance between the North and South Poles. Like the other lines of latitude, it’s based on the Earth’s axis of rotation and its orbit around the sun. It is the longest of Earth’s five circles of latitude, the others being the polar circles, and tropical circles. This is because of how the Earth bulges around its centre.

The Equator is just under 25,000 miles long, wrapping around the entire Earth. The Equator divides the Earth into northern and southern hemispheres, with both experiencing different amounts of daylight at different times. This, weather, climate and the seasons we experience are a result of the Earth’s tilt on its axis and its orbit around the sun. The northern and southern hemispheres are either turned toward or away from the sun depending on the Earth’s position whilst it’s orbiting the sun.

When the Sun is directly above the Earth’s Equator, sunlight shines perpendicular to the Earth’s axis, and all latitudes have a 12-hour day and 12-hour night. The Sun passes directly over the equator twice a year, on the March and September equinoxes.

Credit: twinkl

Picture credit:  Google