This interactive map shows the Tropic of Cancer, Tropic of Capricorn, and the subsolar point (the location where the sun is directly overhead at noon) for any day of the year.
The map is a great way to demonstrate, among other things, the effects of the Earth’s orbital motion. To track the Sun at its zenith, use the slider on the website, where you can select any date between January 1 and December 31.
The map, of course, confirms the well-known laws and relationships – on June 21, the sun’s rays fall vertically on the Tropic of Cancer, and summer begins in the Northern Hemisphere. Similarly, around December 22, the sun’s rays fall vertically on the Tropic of Capricorn, and winter begins in the Northern Hemisphere.
Why does the sun’s position change throughout the year? As the creators of the visualization explain, The Earth’s axial tilt (approximately 23.4 degrees) causes the sun to be directly overhead at different latitudes throughout the year. This causes the subsolar point to change, moving between the Tropic of Cancer and the Tropic of Capricorn as the Earth orbits the sun. This phenomenon is further illustrated with a seasonal animation, a link to which can be found on the tool’s website.
