June 21 marks the summer solstice, the longest day of the year for the Northern Hemisphere, which includes India. This astronomical event occurs when the Earth's axial tilt is most inclined towards the Sun, resulting in the longest day and the shortest night.
The Longest Day
Summer solstice occurs when the Earth's axis is tilted about 23.5 degrees relative to its orbit around the Sun. On this day, the North Pole is tilted closest to the Sun, allowing the Sun to reach its highest position in the sky at noon. This results in regions in the Northern Hemisphere experiencing extended daylight hours.
In India, the duration of daylight depends on the location. For instance, in New Delhi, if the sun rises at 5:23 am and sets around 7:23 pm, it gives around 14 hours of daylight. Cities closer to the equator, like Chennai, will have slightly shorter daylight hours compared to those farther north, such as Delhi and Mumbai.
Significance of Summer Solstice
Traditionally, the solstice marks the longest day and the start of summer. The event has fascinated civilisations for thousands of years. Ancient Greeks like Eratosthenes used the solstice to measure Earth's size accurately. Stonehenge and Machu Picchu were built to align with the sun during solstices. In Egypt, the Great Pyramids and Sphinx were aligned with the solstice sunset, showing ancient people's understanding of the Sun's movements.
The summer solstice has been celebrated in various cultures throughout history. In India, it coincides with the International Day of Yoga. Hundreds of mass yoga events are held on this day across the country.
As the Earth continues its orbit around the Sun, the days will gradually shorten after the summer solstice, leading up to the winter solstice in December, which will be the shortest day of the year.
