The Tropic of Capricorn is the southernmost latitude where the Sun can be directly overhead. Its northern equivalent is the Tropic of Cancer.

The Tilt of the Earth

As at June 2024 the earth is tilted at an angle of 23.43610° or 23°26’09.9″. This is known as obliquity and is what causes the seasons.

The Tilt Changes

The Earth’s axial tilt oscillates between 22.1 and 24.5 degrees over a period of about 41,000 years. This change in obliquity is caused by gravitational forces from the Sun, the Moon, and other planets.

Note – this is not precession.

How this Affects the Tropic of Capricorn

This ‘obliquity of the ecliptic’ is currently decreasing which means that the Tropic of Capricorn is moving northwards each year.

Currently, the average value of the tilt is decreasing by about 0.468″ per year which translates to 15 metres per year.

Tectonic Plate Movement

The north-east movement of the indo-Australian tectonic plate is about 70mm per year and affects the Tropic of Capricorn.

Travellers should note the latitude displayed on their GPS receiver whenever they pass a Tropic of Capricorn marker. The most commonly seen markers are just south of Newman opposite the Capricorn Roadhouse on the Great Northern Highway, north of Minilya on the North West Coastal Highway, and south of Coral Bay on the Minilya-Exmouth Road.

The Tropic of Capricorn is the dividing line between the Southern Temperate Zone to the south and the tropics to the north. In Western Australia north of the Tropic of Capricorn and south of the Kimberley is generally considered to be the Pilbara.

References
www.timeanddate.com

 

© Kim Epton 2016-2024
301 words, one photograph.

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