As yoga goes international on June 21 at International Yoga day, the date actually has a very desi, mythological connection.People the world over embraced International Yoga day on the dawn of June 21 by posting photos on social media. In India many politicians were seen leading Yoga programs in cities while Prime Minister Narendra Modi himself led a large gathering at Rajpath Road in the country's capital of Delhi.Read - In pictures: How politicians did their bit for International Yoga DayLast December, the United Nations General Assembly adopted the India-led resolution declaring June 21 as 'International Day of Yoga' which saw 175 out of the 193 nations joining as co-sponsors making it the highest number ever for any resolution in the history of the UN General Assembly.But why was June 21 selected as the day to commemorate the 6,000 year old practice?Scientifically, June 21 is the day of the Summer Solstice, when the tilt of a planet's axis in the northern hemisphere is most inclined toward the star that it orbits - in our case, the Earth and the Sun.June 21 is considered the longest day of the year with the sun rising early and setting late for the northern hemisphere. Many countries from Canada to Iran mark this day with festivities.But science aside, the summer solstice is also considered an important day in Indian mythology as it marks an event that could be considered the start of Yogic science.According to an article in the Times of India, written by Sadhguru Jaggi Vasudev, Shiva, in the yogic culture, is seen as the Adiyogi, or the first yogi. When people saw the Adiyogi, they flocked to him in the hope for enlightenment but left as he stayed oblivious of their presence. However, Seven people stayed insistent to learn from him but Shiva refused claiming that a lot of preparation was to be done.The seven people then sat determined through 84 years of sadhana, after which Shiva took notice of them as the sun was shifting from the northern to southern run which was the day of the Summer Solstice. It is said that he could no longer ignore them as they were brimming with knowledge.When the next full moon arose 28 days later, Adiyogi transformed himself into Adi Guru and started teaching the ways of the yogic science to his disciples.Also Read - Why I didn't do Yoga today, and other rants