The Solar Calendar and the celebrations honoring the seasons is just one of the thousands of contributions from the Iranian global citizens to the world. Nearly to 4000 years ago, the astronomical phenomena of 2 Solar equinoxes was discovered by Zoroastrians living in Persia ( Iran.) The Spring and Fall equinox fall on the date when the day and night are each approximately 12 hours in length, marking the first day of spring and fall.

The current Iranian Solar Calendar is a 4 season calendar based on equinoxes and solstices.  The seasonal changes are an essential part of human understanding of time and nature. Celebrations like Nowruz, Mehregan, Yalda, and Chelle Tamouz not only highlight the calendar’s scientific basis but also its cultural importance in marking the passage of time through natural events.

The seasons of solar calendar occur as the Earth’s axis is tilted at an angle of about 23.5 degrees relative to its 90 degree angle around the Sun. This tilt causes the seasonal variations we experience due to the changing angle of sunlight hitting the Earth, leading to the solstices and equinoxes. This combination creates the 4 magical seasons on planet earth.

Though the solar calendar was recognized 4,000 years ago, it was significantly refined 1,000 years ago. This accuracy of the Solar calendar is attributed to Omar Khayyam, a Persian polymath who made global contributions in the disciplines of Science, Astronomy, philosophy, mathematics, and poetry.  Khayyam’s work was critical in increasing the precision of the calendar year length, months, and days bringing it very close to the tropical year length used today. Khayyam’s solar calendar continues to be a globally accepted calendar and one of the most precious gifts to mankind. The discovery of the equinox and solstice and subsequent solar calendar is known around the world and still celebrated by 400 Million people in 26 different countries.

The four seasons of the Solar calendar follow:

• Nowruz: The celebration of  Persian New Year beginning on the day of the Spring equinox
• Mehregan: The celebration honoring the divine Zoroastrian named Mithra falls on the day of the fall equinox
• Yalda: The celebration of light over darkness begins on the day of winter solstice, the day of the least hours of sunlight.
• Chelle Tamouz: The celebration of the summer solstice, the day with the the most hours of sunlight.

For millenniums, Iranian people have honored each change of season through joyous celebrations of life and embracing  the new season with positive energy and renewed motivation