June 21 is the longest day of the year for those living in the Northern hemisphere. What is the shortest day of the year for those living in the Southern hemisphere?

The Earth's axial tilt causes seasons to be reversed between the Northern and Southern Hemispheres. On June 21, the Northern Hemisphere is tilted most closely toward the Sun, resulting in its longest day of the year, known as the summer solstice [3]. Conversely, during this same period, the Southern Hemisphere is tilted away from the Sun, experiencing its shortest day and longest night [3]. This event is referred to as the winter solstice in the Southern Hemisphere [2][t2]. While December 21 marks the shortest day for the Northern Hemisphere, it is the longest day for the Southern Hemisphere [2][t8]. Therefore, the date that serves as the longest day for the North (June 21) is simultaneously the shortest day for the South [t2][t9]. Equinoxes in March and September represent periods of equal day and night globally [c3].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 12: Earth, Moon, and the Sun > 12.2.2 Seasons on the Earth > p. 179
2. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Winter Solstice > p. 253
3. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Equinox > p. 254