45th parallel south

Line across the Earth
45°
45th parallel south

The 45th parallel south is a circle of latitude that is 45° south of the Earth's equator.

Highway sign marking the 45th parallel in New Zealand.

It is the line that marks the theoretical halfway point between the equator and the South Pole. The true halfway point is 16.2 km (10.1 mi) south of this parallel because Earth is not a perfect sphere, but bulges at the equator and is flattened at the poles.[1]

Unlike its northern counterpart, almost all (97%) of it passes through open ocean. It crosses the South Atlantic Ocean, the Indian Ocean, Australasia (New Zealand and just south of Tasmania), the Southern Ocean, and Patagonia.

At this latitude, daytime lasts for 15 hours, 37 minutes during the December solstice and 8 hours, 46 minutes during the June solstice for the dates in 2024.[2] This holds true regardless of longitude. The midday Sun stands 21.17° above the southern horizon at the December solstice, 68.83° at the June solstice, and exactly 45.0° at either equinox.

  1. ^ "The Half-Way to the Pole Line". May 2, 2006. Archived from the original on 2006-05-02.
  2. ^ US Department of Commerce, NOAA. "ESRL Global Monitoring Laboratory - Global Radiation and Aerosols". gml.noaa.gov. Retrieved 2024-08-15.