There are mysteries which are beyond human understanding and people never tend to solve those mysteries but recently a bunch of tweets started popping up where people were wondering about the 10 missing days from the calendar of October 1582.
October 1582 does not look like other months. In 1582 October 4 is followed by October 15 and the 10 days in between are missing.
However, American astrophysicist Neil deGrasse Tysonthere has an answer for this mystery. He said that in 1582 the Julian calendar, with a Leap Day every four years, had accumulated 10 extra days relative to Earth’s orbit.
So Pope Gregory jump-started his new and exquisitely accurate calendar by cancelling 10 days that year, where October 4 was followed by October 15.