Parallels and meridians

Parallels are imaginary circular lines perpendicular to the Earth's axis, and their reference is the zero parallel, or equator. They are used to determine latitude, which is the angular distance between the equator and any point on the planet.

The meridians are semicircular imaginary lines that pass through the North and South poles. They are used to measure the longitude of a point on Earth, with respect to the meridian 0, or Greenwich meridian.

What are parallels?

Parallels are man-made lines, with an East-West direction. Each of these lines is numbered, from 0º, which is the equator or equatorial line (the only line that is a circle in strict terms, and that crosses the center of the earth's globe), to 90º at the North Pole and the South Pole.

Main parallels

The equator, or parallel 0º, divides the planet into two hemispheres: North and South. It is complemented by other 4 main parallels, with which a distinction is made since they correspond to a specific position of the Earth, with respect to its orbit of the Sun:

• Arctic Circle: it is the northernmost parallel. This parallel is the area in which the polar night (December) and the midnight sun (June) of the Northern Hemisphere occur..
• Tropic of Cancer: it is the northernmost parallel, characterized because it is the place where the Sun reaches its zenith, during the June solstice.
• Tropic of Capricorn: it is the southernmost parallel in which the Sun reaches its zenith, during the December solstice.
• Antarctic polar circle: it is the southernmost parallel, where the polar night (June) and the midnight sun (December) of the southern hemisphere occur.

Parallels allow determining the position to the North or South of any point on the planet with respect to the equator, which is known as latitude..

What are meridians?

The meridians are imaginary lines, which go from the North Pole to the South Pole, so they are shaped like semicircles. They divide the Earth into two hemispheres: eastern and western.

Main meridians

There are 360 ​​meridians: 180 to the west and 180 to the east of the zero meridian. The main ones are:

• Greenwich Meridian: it receives that name in honor of the contributions of the Greenwich Observatory, in London. Furthermore, said parallel "passes" through the location of said observatory. Also known as meridian 0.
• Antimeridian: so called because it opposes the Greenwich meridian, forming an angle of 180 degrees with respect to the 0º meridian. It is also known as the 180th meridian.

Since 1884, the 0º meridian has been used to establish world time zones. From it, and towards the East, the hour increases, and towards the West, it decreases.

For its part, the antimeridian is the reference point for the international date change line..

The distance of any point on the planet with respect to the meridian 0º, either east or west, is known as longitude.

See also

• Solstice and equinox
• Map types
• Rotational and translational movement