Users social networks drew attention to an unusual feature of the calendar.
This was reported by URA-Inform with reference to IFLScience.
In particular, when scrolling to 1582, October 4 is immediately followed by October 15, and 10 days between these dates are missing. This is not an error, but a historical fact – these days really “disappeared”.
As IFLScience explains, the Catholic Church switched to the Gregorian calendar in October 1582. Before that, it used the Julian calendar, introduced by Julius Caesar in 45 BC. The main difference of the Gregorian calendar is its adjustment for leap years: it eliminates extra days in years that are divisible by 100 unless they are divisible by 400.
This was a major change for the Catholic Church, as the date of Easter no longer coincided with the vernal equinox on March 21, as determined by the Council of Nicaea in 325. The equinox had gradually shifted, and by the 16th century it fell on March 11. To restore the correct order, Pope Gregory XIII decreed to “remove” the equinox. 10 days from the calendar.
The transition to the Gregorian calendar was made on October 4, 1582: after this day, October 15 came immediately. October was chosen to avoid overlapping with important Christian holidays.
That is why today's calendars, including those on the iPhone, do not include dates from October 5 to 14, 1582, because in real history they never existed.
Recall that earlier it was reported that it became known where the most ancient pyramids are: and it is not Egypt.