The 2026 Mid-Autumn Festival in Chicago is early due to the shifting of the lunar calendar. The festival, which traditionally celebrates the harvest moon, is based on the lunar cycle, and its date varies each year. In 2026, the festival will occur earlier than usual because the moon's phase aligns with the calendar earlier than in previous years.

The Mid-Autumn Festival is typically celebrated on the 15th day of the eighth lunar month. This year, the festival falls on September 9th, which is earlier than the average date of the festival. The reason for this early celebration is the astronomical alignment of the moon's phases. The moon's orbit around Earth is not perfectly circular, causing the time between full moons to vary slightly each month. In 2026, the full moon occurs earlier in the lunar month than usual, pushing the festival date forward.

According to the Chinese Lunar Calendar, the Mid-Autumn Festival is determined by the actual phase of the moon. The calendar is based on the observation of the moon's cycles, and the festival is celebrated when the moon is at its fullest. In 2026, the full moon will be on September 9th, which is earlier than the average date of the festival. This early occurrence is a result of the moon's orbit and the varying lengths of the lunar months.

Data from the National Aeronautics and Space Administration (NASA) supports this explanation. NASA's lunar data indicates that the full moon in September 2026 will occur on September 9th, which is earlier than the average date of the Mid-Autumn Festival. This early date is due to the moon's orbit and the varying lengths of the lunar months, which are influenced by the moon's elliptical orbit around Earth.

In conclusion, the 2026 Mid-Autumn Festival in Chicago is early due to the moon's phase aligning with the calendar earlier than usual. This alignment is a result of the moon's orbit and the varying lengths of the lunar months, as supported by data from NASA.