While researching biographical information on Isaac Newton, my students found conflicting dates for the scientist’s birth (December 25, 1642 and January 4, 1943). This is due to a difference in the Julian and the Gregorian calendars. At the time of Newton’s birth, England had not yet adopted the Gregorian calendar, so there is an “old” date for Newton’s birth and a “modern” date. (England changed calendars in 1752.)
Our modern western calendar seems like a fixed, unvarying system of measuring time, but it’s actually the result of lots of science and lots of tinkering. This great little video helps explain:
Some people think our calendar needs to be overhauled again. This article in Scientific American suggests the calendar could be revised to be more business-friendly.