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You are here: Home / Universe / How Old Is The Earth?

How Old Is The Earth?

July 23, 2020 by Karen Hill

To figure out the age of the earth, it is important to know how old the rocks on it are. Scientists can date rocks by measuring the amount it of radioactivity, or rays of energy, they give off.

All rocks contain some uranium, which causes radioactivity, and that uranium give off invisible rays of energy which slowly change the uranium into lead. Scientists know how long it takes for uranium to change into lead, so by comparing how much uranium and how much lead are in the rocks, they can determine the age of the rocks.

By this method, scientists have determined that some granite gneiss rocks found in Tanzania, East Africa, are about 3.5 billion years old!

But bits of meteors that have fallen to earth are even older. They are parts of other planets in our solar system, and seem to be 4.5 billion years old! Most scientists believe that our whole solar system started off at the same time. We can therefore figure the planet earth to be about 4.5 billion years old.

Related Facts

  • How did Marie Curie discover radium and Where did radium come from?
  • Who Discovered Radioactive Dating and How are radioactive decaying elements used to calculate the age of rocks?
  • Where does Uranium Come from and How is Uranium Mined?
  • Why Can’t Superman See Through Lead With His X-Ray Vision?
  • Which Part of Niger Has Uranium Mines?
  • Which Explorers First Explored the Continents of the World?

Filed Under: Universe

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

Previous Post: « How Is the Earth Like an Onion?
Next Post: What Are Clouds Made Of? »

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