What is Summer and Winter Solstice? Did you know that when people in New York, USA, are enjoying a beautiful summer and having their vacations with family, people in Buenos Aires, Argentina, will be in the comforts of their home, away from the chill of a winter?! Further, their summer days are longer, and the winter days are short and gloomy. One can fly from a pleasant summer to a harsh winter in about 11 hours.
This phenomenon is known as solstice, which is the cause of seasons on the Earth, and this has nothing to do with the sun’s proximity or remoteness. While many sites in the world have been excellently built to capture the movement of the sun, the Gavi Gangadhareshwara Temple in Bengaluru cannot be missed.
Before you visit that temple, know about the Earth’s uniqueness, responsible for the climates we experience. How exactly does it happen?
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Summer Solstice in the Northern Hemisphere (NH)
Also called the ‘June solstice’ (between June 20 and 22), it happens when the sun’s rays fall directly (90 degrees) on the Tropic of Cancer in the northern hemisphere. The sun’s rays make a 23.5-degree angle with the Equatorial plane. During these days, NH experiences the longest day of the year, with maximum intensity of the sun’s rays.
Winter Solstice in the Southern Hemisphere (SH)
The December solstice (between Cec 20 and 23) occurs when the sun’s rays fall directly (90 degrees) on the Tropic of Capricorn in the southern hemisphere (winter solstice SH). SH experiences the shortest day of the year, with a minimum intensity of the sun’s rays.
What is the mechanism?
Nobody knows why there is a tilt to the Earth’s axis, but this tilt is the reason for the observations and, hence, the seasons on Earth. The Earth revolves around the sun without changing the tilt angle, as seen in the diagram below.
While the Earth takes one year to go around the sun once, it takes 24 hours to go around itself. When it is going around the sun, the day and night durations vary based on its position along the elliptical orbit around the sun.
Considering the NH, the days are the longest during the summer solstice, and the nights are the shortest. Looking at the diagram, the earth’s NH is facing the sun, and hence, the north pole and Tropic of Cancer receive direct sunlight, while the Equator receives light at an angle, which will be less.
Similarly, observing the earth’s position during the winter solstice, direct sunlight falls on the Tropic of Capricorn and, once again, less light on the equator. This is due to the South Pole facing the sun and the North Pole going behind due to the tilt.
What are Equinoxes?
When the Earth reaches a position where both its NH and SH receive equal amounts of sunlight, it is called an equinox. At these positions, the sun’s rays are directly on the equator (90 degrees) at midday; all places on the equator or slightly above or below will experience equal day and night.
Earth experiences this phenomenon, but the places on the Equator and nearby will have direct sunlight, while the days and nights are equal.
About the cave temple in Bengaluru?
Gavi Gangadhareshwara Temple in Bengaluru is a testimony to the skills and intuition of our ancestors. They were both religious and scientific at the same time. It seems superstitions might have cropped up only in the recent past.
This temple boasts of the accuracy with which the sun’s rays fall on the face of the deity, Shiva, on January 14 of each year, year after year! The architectural marvel is on one side, and the astronomical prowess is on the other. Recent research by Astrophysicists from Bengaluru discovered evidence that led to thinking that the temple was more than just a religious, holy place of worship.
Every year on January 14, the sun illuminates the idol of the deity inside the cave on Makara Sankranti. The rays from the Southwestern part of the temple pass through a stone-carved window and between the horns of a Nandi statue before falling on the idol in the garbhagudi.
Two other pillars decorate the temple, ‘avarana’, the eastern and western pillars. They are more than just symbolic. As the study revealed, it is positioned exactly in the direction of the June 22nd sunset and the December 22 sunrise.
It is amazing that Hindu astronomers were aware of many aspects of astrophysics, which Western scientists recently discovered. Take, for example, the phenomenon called ‘precession.’
What is precession?
- The Earth’s tilt of 23.5 slowly changes in a circular manner due to the gravitational forces of the Sun and Moon on Earth.
- This circular motion may be compared to the wobbling of a top when spinning slows down.
- It takes ~ 26,000 years to complete one cycle and is called a Platonic year.
- Earth’s axis is currently pointing towards Polaris, our North Star, but due to precession, it will be pointing to Vega, which will be our North Star in 14,000 CE!
- Precession also shifts solstices and equinoxes over long periods.
Hindu astronomers were aware of the precession phenomenon while carving the stone window; this was the ‘Ayanamsha’ or the gradual shift of the equinoxes that they used to calibrate and align structures with celestial events.
Makara Sankranti celebrates the beginning of ‘Uttrayana’, the sun’s northward movement. This happens a few weeks after the winter solstice (Dec 22). The word Makara means Capricorn, and the sun enters Capricorn on January 14, as per the sidereal zodiac (based on the actual positions of the 12 constellations along the ecliptic, the path of the sun as seen from Earth.) used in Indian astronomy.
Conclusion
Our ancestors were wise beyond their time; using the sidereal zodiac system gave them the advantage of ensuring alignment with the cosmos and yet having deep cultural, astronomical, and astrological significance. They can no longer be dismissed; India needs to spearhead rekindling the study of Surya Siddhanta, not politics for power.
We were a great nation, but are we today? We need to focus on achieving this status again.
