Isaac Newton, 300 years on: the 2027 anniversary

Why Newton's death has two dates

Newton died in the early hours of 20 March 1727 in the English reckoning of the day, at his house in Kensington, then a village west of London. He was 84. Most of Catholic Europe had switched to the Gregorian calendar in 1582, but Britain kept the older Julian calendar until 1752. By the 1700s the Julian calendar ran eleven days behind, so 20 March in London was 31 March in Paris.

There is a second wrinkle. In England the legal year began on 25 March, not 1 January. A death on 20 March therefore still fell in the year 1726, and careful writers put “1726/7” to show both counts. Modern historians usually give 31 March 1727 (New Style), or 20 March 1727 with the year adjusted. Both refer to the same day.

His birth works the same way. He was born on Christmas Day, 25 December 1642, by the Julian calendar, which is 4 January 1643 by ours (in the 1600s the gap was ten days). That is why some books say 1642 and others 1643, and why his birth tercentenary was marked in 1942. Because of the war, the Royal Society's own Newton Tercentenary Celebrations were held in July 1946.

Newton 300: what is planned for 2027

South Kesteven District Council, the council for the area around Grantham where Newton was born and went to school, has proposed a programme called Newton 300 to mark the anniversary on or around 31 March 2027. In February 2026 its culture and leisure committee discussed the plan, and the council said it would invite arts groups and other organisations to take part, subject to approval in its budget. As of October 2026 the details had not been published, so check the council's announcements.

Woolsthorpe Manor, his birthplace near Colsterworth, belongs to the National Trust, which has owned it since the 1940s. It keeps the room where he is said to have worked during the plague years and an old apple tree in the orchard traditionally linked to the falling apple story. Westminster Abbey, where he is buried, and Trinity College, Cambridge, where he lived for more than thirty years, are the other places closely tied to him. We had not found published 2027 programmes from the Royal Society, Trinity or the Abbey by October 2026; it is worth watching their sites.

Newton's life in key dates

What the Principia did

The Principia (Mathematical Principles of Natural Philosophy) is three books in Latin. Book I sets out the three laws of motion and works out how bodies move under forces, Book II deals with motion through resisting fluids, and Book III, “The System of the World”, applies it all to the heavens. Its central claim is that one force, gravity, varying with the inverse square of distance, explains why apples fall, why the Moon orbits the Earth, why planets follow Kepler's elliptical orbits, and why the tides rise and fall. The same law runs on Earth and in the sky.

It was hard reading even for experts, and Newton wrote it in geometry rather than the calculus he had invented. Its effect was still enormous. Halley used its methods to predict that a comet seen in 1682 would return around 1758, and it did. In the second edition (1713) Newton added the General Scholium, in which he says he has explained the effects of gravity but not found its cause, and refuses to guess:

Newton was also a devoted, unorthodox Christian who wrote more on theology, biblical prophecy and alchemy than on physics. He privately rejected the doctrine of the Trinity and kept those papers unpublished. A fair portrait keeps both sides, as well as his fierce disputes with Hooke and Leibniz. Our Newton vs Galileo comparison sets his work against what came before.

Sourced words from Newton

The most famous line comes from a letter to Hooke, his rival, which mixes courtesy with what some historians read as a jab:

When the clergyman Richard Bentley asked him about the Principia, he credited not genius but work:

Three years after his death, the poet Alexander Pope wrote the epitaph that captured how the 1700s saw him: “Nature and Nature's laws lay hid in night: / God said, Let Newton be! and all was light.”

The apple is real in one sense: Newton told the antiquary William Stukeley in 1726 that the idea of gravitation came to him as he sat in a garden and an apple fell. Nothing says it hit his head. Our article Did an apple fall on Newton's head? traces the story.

How to mark the anniversary in class

• Calendar puzzle: give students “20 March 1726/7” and ask them to convert it. They need the ten or eleven day gap and the 25 March new year. Then ask why Britain changed in 1752.
• Prism experiment: with a glass prism, a torch or sunlight and a white card, repeat Newton's split of white light into colours, then use a second prism to try recombining them, as he described in his 1672 paper.
• Laws of motion stations: three tables, one law each, with a ball, a trolley and a balloon, and students write the law in Newton's order before testing it.
• Read the source: the opening Axioms, or Laws of Motion, from Andrew Motte's 1729 English translation of the Principia is two pages and is free online.
• Interview Newton about 1687: students prepare questions about Halley's visit, Hooke and the cost of printing. They can practise them by voice with an AI recreation of Isaac Newton on Yuga. It is not Newton and can get things wrong, so every claim in the final project should be checked against the Correspondence or a biography.

Our questions to ask Isaac Newton list has grouped questions and notes on what the sources say.