When is the sun directly overhead?

The longest day of the year occurs this coming Saturday. In the Northern Hemisphere, the summer solstice is on June 21st. This is the day when the subsolar point - the location on Earth where the Sun is directly overhead at solar noon - reaches its northernmost position, directly above the Tropic of Cancer.

The subsolar point moves north and south throughout the year as the Earth orbits the Sun. At the summer solstice, it's at its highest point in the Northern Hemisphere, marking the beginning of summer and the day with the most daylight. Conversely, during the winter solstice around December 21st, the subsolar point is at its southernmost position, directly above the Tropic of Capricorn, resulting in the shortest day of the year in the Northern Hemisphere.

The animated map above shows the subsolar point moving between the Tropic of Cancer and the Tropic of Capricorn from June 16th (today) through the winter solstice. You can explore this for yourself on Tropics of Cancer and Capricorn - an interactive map that displays both tropics and the subsolar point for any day of the year. Use the day slider in the map sidebar to select a date. The line indicates where on Earth the Sun is directly overhead at noon for the selected day.

By coincidence, the road on which I live is perfectly aligned with the rising sun on the morning of the summer solstice. I discovered this fascinating detail on Solstice Streets, an interactive map that highlights roads in cities around the world which align with the sunrise on either the summer or winter solstice. The site blends astronomy with urban design, revealing how some modern streets unintentionally - or perhaps in some cases intentionally - mirror ancient alignments that celebrate solar events.