For Muslims, the day of Eid is either determined by lunar calculation or visual observation. Often this splits the community due to theological differences. This year Eid is predicted to be on either Friday or Saturday (21-22/04).

Asking ChatGPT for clarification however gives a wildly different answer of 21-22/05.

This might be due to some error in calculating the difference from the Islamic to Gregorian calendar.

Full CHATGPT response below:

Determining the exact day of Eid al-Fitr on the Moon is challenging, primarily because Islamic holidays are based on the lunar calendar and the sighting of the new moon. Since you would be on the Moon, the traditional way of sighting the new moon wouldn't be applicable.

If you were on the Moon, the most practical solution would be to coordinate with Earth-based Islamic calendars to determine when Eid al-Fitr should be observed. In 2023, Eid al-Fitr is expected to be around May 21st or 22nd, depending on the sighting of the new moon on Earth. You could choose to observe the holiday on the same day as the location on Earth you most identify with or follow.

In the future, if there is a lunar settlement, there might be a standardized approach for tracking time and religious observances in coordination with Earth. However, no such system currently exists.