Tropic of Cancer
Northernmost latitude where the Sun appears directly overhead.
The Tropic of Cancer is the Earth's northernmost circle of latitude where the Sun can be seen directly overhead, occurring on the June solstice. It is one of the seven major circles of latitude and marks the northern boundary of the tropics, with its position determined by Earth's axial tilt, which changes over time.
- type
- Circle of latitude
- northern_counterpart
- Arctic Circle
- southern_counterpart
- Tropic of Capricorn
- named_after
- Zodiacal Cancer (Latin: Crab)
Lore & Background
The Tropic of Cancer was named in the last centuries BC, when the Sun was in the zodiacal Cancer at the June solstice. Due to the precession of the equinoxes, the Sun is now in Taurus at that solstice. The word 'tropic' comes from the Greek 'tropē', meaning turn or inclination, referring to the Sun appearing to 'turn back' at the solstices. Geopolitically, the Tropic of Cancer is known as the southern limitation on the mutual defence obligation of NATO; member states are not obligated to defend territory south of this line.
Reader's Guide
The Tropic of Cancer holds significance as a fundamental reference line for geography, astronomy, and geopolitics. Astronomically, it marks the northernmost point where the Sun can be directly overhead, defining the June solstice and the boundary of the tropics. Its drifting position, caused by Earth's axial precession and tilt variations, requires continuous updating for accurate mapping. Geographically, it separates the tropics from the subtropics and North Temperate Zone, and its climate is generally hot and dry, with exceptions in highland and coastal areas. Its geopolitical role as the southern limit of NATO's mutual defence obligation adds a modern political dimension. The line passes through 17 countries and 8 water bodies, and its highest adjacent mountain is Yu Shan in Taiwan. Understanding the Tropic of Cancer is essential for grasping Earth's axial tilt, seasonal cycles, and the dynamic nature of planetary reference systems.
Did You Know?
- The word 'tropic' comes from the Greek 'tropē', meaning turn or inclination, because the Sun appears to 'turn back' at the solstices.
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