23½° S
Explanation
The Earth's surface is divided by specific imaginary lines of latitude that define climatic zones and the distribution of solar insolation. These latitudes are determined by the Earth's axial tilt of approximately 23.5° relative to the plane of its orbit around the Sun.- 23½° N is incorrect: 23½° N represents the Tropic of Cancer. It marks the northernmost latitude at which the Sun can be directly overhead (occurring during the June Solstice).
- 66½° N is incorrect: 66½° N represents the Arctic Circle, marking the southern limit of the area within which, for one day or more each year, the Sun does not set or rise.
- 23½° S is correct: 23½° S represents the Tropic of Capricorn. It marks the southernmost latitude where the Sun can be directly overhead (occurring during the December Solstice).
- 66½° S is incorrect: 66½° S represents the Antarctic Circle.
Key Takeaway: The Tropic of Capricorn (23½° S) defines the southern boundary of the Torrid Zone, the region of the Earth that receives the most direct solar radiation.