Isaac Newton was a famous scientist and mathematician from England who lived long ago. He was born in the manor house at Woolsthorpe. His family were farmers. His father died before Newton was born. At school, his reports called him idle and inattentive. His mother took him out of school to run the family farm. But he returned to school and went on to university. He went to Trinity College, part of Cambridge University.

Then a sickness called the plague closed Cambridge University, so Newton went home to Woolsthorpe. While away from Cambridge because of the plague, Newton began important work in mathematics, light, physics and astronomy. He did all this in less than two years. Newton had early versions of his three laws of motion by 1666. He began working on them in a notebook at the family farm. Newton also shone sunlight through a glass prism and saw a band of colors.

Newton split white light into colors with one prism. Then he used a second prism to join the colors back into white light. White light is made of all the colors of the rainbow, and Newton showed this. Telescopes with glass lenses showed blurry colors. A mirror reflects all colors of light by the same amount, so a mirror telescope fixes this. Newton made a telescope that uses a mirror.

Newton's first law says a still object stays still. A moving object keeps moving the same way, unless a force acts on it. His third law says that when one object pushes on another, the second pushes back just as hard in the opposite direction. Newton wrote that if you press a stone with your finger, the stone also presses on your finger. His second law says a bigger force changes an object's motion more. People write it as F=ma. That means force equals mass times acceleration.

Newton told a story about watching an apple fall from a tree. No one knows for sure if an apple really fell the way the story says. The part where it hits him on the head is called a myth. What Newton did see was that the Moon circling Earth and an apple falling from a tree follow the same basic rules of motion. He said that everything pulls on everything else. He called this pull gravity.

The farther apart two things are, the weaker the pull of gravity between them. If two objects are twice as far apart, the pull of gravity between them is only one fourth as strong. Newton showed that if gravity gets weaker with the square of the distance, then gravity on Earth's surface correctly predicts how long the Moon takes to orbit. The Earth pulls on the Moon with gravity. That pull keeps the Moon going around the Earth.

Newton wrote a famous book about how things move. It is called the Principia. His friend Edmond Halley paid to have the Principia printed. Newton's laws of motion and gravity became the base of classical mechanics. That is the study of how large things move. In 1669 Newton became the Lucasian Professor at Cambridge. It is a professor's chair that Isaac Barrow had held. In 1703 he was elected President of the Royal Society, a group of scientists.

At the Royal Mint, Newton helped take old coins out of use. The Mint replaced them with more reliable ones. Newton lived to be 84 years old. He is buried in Westminster Abbey in London. Near the end of his life Newton said he felt like a boy on the seashore. He felt he was finding a smoother pebble or a prettier shell, while the great ocean of truth lay undiscovered. Newton's laws are still used to reach the Moon, Mars and other places beyond Earth.

Words to know

• plague: a bad sickness
• prism: light-splitting glass
• gravity: pull between things
• orbit: path around something
• mechanics: study of motion