• Question: how old is the earth?

    Asked by oliwiabieber to James V, Davie, Gemma, James P, Nuala on 25 Jun 2012. This question was also asked by karolinaparker, riob88.
    • Photo: James Verdon

      James Verdon answered on 25 Jun 2012:

      Hi oliwiabieber and karolinaparker,

      The earth is about 4.6 billion years old. That’s 4,600,000,000 years. Humans emerged in Africa about 200,000 years ago, so we have been in existence for something like 0.0004% of earth’s history. We really are just a little blip.

      We know the age of the earth from radiometric dating. There are lots of radioactive elements on the earth. These undergo decay at constant rates. So we can look at how much is left, and how much has decayed, and work out how long that amount of decay would take, and that gives us the age of the earth.

    • Photo: James Pope

      James Pope answered on 2 Jul 2012:

      Hi oliquabieber, karolinaparker and riob88,

      Yep as James V says, 4.6 billion years old! If all of the Earth’s existence was a day on Earth humans would appear in the very last second of the day. Despite this, no other single species has had such an impact on the planet and it’s environment.

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