You may have heard that an apple hit Isaac Newton on the head. You may have heard that this is how he found gravity. Newton was a scientist from England. He lived long ago. He 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.

Newton was born in the manor house at Woolsthorpe, in England. His family were farmers. Newton did not make gravity. He said that everything pulls on everything else. He called this pull gravity. He also saw that the Moon circling Earth and an apple falling from a tree follow the same basic rules of motion.

The Earth pulls on the Moon with gravity. That pull keeps the Moon going around the Earth. The Sun's gravity pulls on the planets. It holds them in their paths around the Sun. The farther apart two things are, the weaker the pull of gravity between them. Newton's ideas helped explain the tides, the rise and fall of ocean water, which come from the Moon's pull.

Newton came up with three laws of motion. His 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 one object can push on another. Then the second pushes back just as hard, in the opposite direction. A heavy object speeds up less than a light object. That is when the same force pushes on each.

Newton's 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 wrote a famous book about how things move. It is called the Principia. It was published in 1687. His friend Edmond Halley paid to have it printed. Newton's laws helped scientists understand how the planets move. They helped explain how the Moon moves around the Earth.

Newton also studied light. He shone sunlight through a glass prism and saw a band of colors. White light is made of all the colors of the rainbow. 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.

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. Queen Anne made him a knight in 1705. So he was called Sir Isaac Newton. Newton's laws are still used to reach the Moon, Mars and other places beyond Earth.

Words to know

• gravity: pull between things
• myth: story, not fact
• force: a push
• telescope: far-seeing tube
• prism: light-splitting glass

The short version

Isaac Newton was a scientist and mathematician from England who lived long ago. He said that everything pulls on everything else and called this pull gravity. He also wrote three laws of motion in his book the Principia, and showed that white light is made of all the colors of the rainbow.

Quick facts

• Newton's three laws of motion and his idea of gravity are still used to reach the Moon, Mars and other places beyond Earth.
• Newton's friend Edmond Halley paid to have the Principia printed. It was published in 1687.
• Newton made a telescope that uses a mirror, which fixes the blurry colors of lens telescopes.
• In 1703 Newton was elected President of the Royal Society, a group of scientists.