On September 22, 2024, at precisely 6:13 PM IST, the September equinox will occur, marking a significant astronomical event. This moment signals the Sun's crossing of the celestial equator from the Northern to the Southern Hemisphere, resulting in nearly equal hours of day and night across much of the globe, including India.
The equinox, which occurs twice a year in March and September, sees the Sun's rays fall directly on the equator. As a result, day and night durations become roughly equal worldwide, offering a temporary pause in the gradual shortening or lengthening of daylight hours, depending on one’s hemisphere.
In the Northern Hemisphere, including India, the September equinox heralds the arrival of autumn. As the Sun moves southward, the region enters cooler months characterised by shorter days and longer nights. This transition traditionally marks the end of the monsoon season and the beginning of crisp, refreshing weather.
Conversely, the Southern Hemisphere experiences the opposite effect. Here, the September equinox signals the onset of spring, with days growing longer and nights shorter as warmer weather and increased sunlight arrive.
While the equinox is commonly perceived as a day of perfect balance between day and night, this is slightly misleading due to atmospheric refraction and the Sun’s apparent size. The equinox is technically defined by the exact moment the Sun crosses the equator.
Following the equinox, the Sun will continue its southward journey, ultimately reaching the Tropic of Capricorn during the December solstice. The September equinox serves as a reminder of Earth’s constant motion and the shifting rhythms of nature as we transition from one season to the next.