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

Line across the Earth
45°
45th parallel south
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.

Around the world

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Starting at the Prime Meridian and heading eastwards, the parallel 45° south passes through:

Coordinates Country, territory or ocean Notes
45°0′S 0°0′E / 45.000°S 0.000°E / -45.000; 0.000 (Prime Meridian) Atlantic Ocean
45°0′S 20°0′E / 45.000°S 20.000°E / -45.000; 20.000 (Indian Ocean) Indian Ocean
45°0′S 147°0′E / 45.000°S 147.000°E / -45.000; 147.000 (Pacific Ocean) Pacific Ocean Tasman Sea
45°0′S 167°8′E / 45.000°S 167.133°E / -45.000; 167.133 (New Zealand)   New Zealand South Island, passing just north of the towns of Oamaru, Naseby, Cromwell and Queenstown, and through the small settlement of Becks
45°0′S 171°6′E / 45.000°S 171.100°E / -45.000; 171.100 (Pacific Ocean) Pacific Ocean Passing just south of Guamblin Island,   Chile
45°0′S 74°23′W / 45.000°S 74.383°W / -45.000; -74.383 (Chile)   Chile Islands in the Chonos Archipelago including James Island and Melchor Island, and Moraleda Channel before reaching the mainland near Macá Volcano.
45°0′S 71°33′W / 45.000°S 71.550°W / -45.000; -71.550 (Argentina)   Argentina Chubut Province
45°0′S 65°35′W / 45.000°S 65.583°W / -45.000; -65.583 (Atlantic Ocean) Atlantic Ocean

See also

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References

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  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.