• Question: how old is planet earth

    Asked by cooliog to Zoe, Sharon, Louise, Jon, Daniel on 23 Jun 2010 in Categories: .
    • Photo: Sharon Sneddon

      Sharon Sneddon answered on 22 Jun 2010:

      It is believed that Earth formed 4.54 billion years ago and life appeared on its surface within a billion years.

    • Photo: Jon Copley

      Jon Copley answered on 22 Jun 2010:

      The Earth formed about 4.54 billion years ago. Geologists know this from measuring the decay of radioactive elements in lead ores preserved from the early Earth.

    • Photo: Zoe Duck

      Zoe Duck answered on 22 Jun 2010:

      4.54 billion years old. The sun is about 30 million years older. The age of the earth was determined by using a method called radiometric dating. For more info on this check out
      http://en.wikipedia.org/wiki/Age_of_the_Earth#Radiometric_dating

    • Photo: Daniel Richardson

      Daniel Richardson answered on 22 Jun 2010:

      about 4 to 5 billion years I think. There ought to be a sell by date written on the antarctic somewhere….

    • Photo: Louise Dash

      Louise Dash answered on 23 Jun 2010:

      About 4.5 million years. We know this from a technique called radiometric dating, which measures the ratio of radioactive isotopes in rocks from the earth’s crust. As no rock can be older than the earth itself we therefore know that the earth has to be at least as old as the oldest rock!

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