Isaac Newton Was Born On Christmas Day – And January 4th

Christmas Day marks the birth of a wise man who revealed eternal truths to humanity and reshaped the course of history: Isaac Newton. Well… sort of. Had he been born elsewhere in Europe, rather than in England, his birthday would have fallen on January 4.

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Newton – the endlessly talented nerd behind the laws of motion, universal gravitation, and groundbreaking advances in optics and calculus – was born in England on December 25, 1642. According to most biographical accounts, he was born three months prematurely, so small that he could have been tucked into a quart mug. Few expected him to survive, let alone change the world.

His birth was a time when the country was being torn apart by the English Civil War. Royalists and parliamentarians were butting heads, religious tensions were boiling over, and political structures were crumbling in a post-medieval meltdown. Amidst the chaos, the Scientific Revolution was gathering momentum, a movement that would soon reach its peak through the work of Newton himself.

England had also just had a messy break-up with the Catholic Church, pissing off the pope and carving its own path toward Protestantism. As a result, the country was still hanging on to the Julian calendar.

Established by the Roman bigman Julius Caesar, hence its name, the Julian calendar is a solar calendar that features 365 days, divided into 12 months, plus a leap day every four years. It functioned reasonably well, but it slightly overestimated the length of the year by about 11 minutes. 

Over centuries, this tiny error amplified and caused the calendar to drift out of sync with the solar year and the seasons. This was especially bothersome for the Catholic Church, which was frustrated because the drifting Julian calendar confused their calculations of Easter's timing.

To remedy the problem, Pope Gregory XIII introduced the Gregorian calendar in 1582. This new calendar was slightly more accurate as it had an average of 365.2425 days per year, as opposed to the 365.25 days of the Julian calendar. 

Most Catholic countries gladly accepted the Gregorian calendar, but Protestant England resisted, unwilling to cut the Catholic Church any slack. They stubbornly held on to the Julian calendar for another 170 years, not switching until 1752, long after Newton’s birth. 

This means that Newton was born on January 4 if you use the Gregorian calendar, which we still do today. The irony is that through this twist of fate, Newton – a reclusive, obsessive, and introspective man with very little in festivities – ended up with a birthday on Christmas Day.