Birthday Confusion

I was surprised by the image that Google placed on its website on January 4th 2010, in honor of Sir Isaac Newton’s birthday. You see, everything I’ve ever read about the man claims he was born on December 25, 1642, Christmas morning. I was puzzled by the fact that Google had it wrong, and further by the fact that no one noticed.


Turns out, we were both right. Come to find out, Newton was born on December 25, 1642  and January 4, 1643.  How is this possible? 

At the time of his birth England was utilizing the Julian calendar. It wasn't until the 1700’s, that England began to adopt the Gregorian calendar.  Countries across Europe had begun to adopt this calender as early as the 1500's.

This "new" calendar system changed the position of the New Year and calibrated the calendar to astronomical processes (ie: # of days the earth takes to circumvent the sun). Because of this change, Historical documents dictate that Newton was born on December 25th. The January 4th date is a calibration to the Gregorian calendar, now in use.  This is sometimes notated by "OS" meaning "Old Style" and "NS" meaning "New Style".  These notations are often used by historians, as a way to more accurately report historical events. 

Other interesting dates and changes include George Washington’s birthday. Some historical accounts claim he was born on February 11, 1731, which would be accurate given the Julian Calendar, but we celebrate this on February 22.  Calibrated correctly his birthday would be written February 22, 1732.

Thomas Jefferson had both dates (Julian and Gregorian) placed on his headstone. This was influenced by England’s adoption of the Gregorian calendar during his lifetime.

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