Question: How long the Earth formed in geologic terms?

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  1. Hi Robert,

    The Earth was formed 4.6 billion years ago. We know this because of dating minerals called zircons – the oldest ones are found in Australia and are called the Jack Hills zircons. <— this website has some more information!
    We can use various dating systems to work out the ages of materials – the most commonly used one for zircons is Uranium Lead (U/Pb) dating. Other dating systems include Argon-Argon dating, Rubidium-Strontium, Samarium Neodymium and Rhenium Osmium dating. The dating system you use depends on the material you are trying to date, as some systems are better for some materials than others.

    Hope that helps!


  2. Hi robert, really good question! Some of my colleagues at CRPG have actually analyzed Xenon gas in rocks from Australia and Africa and have been able to figure out that the Earth and Moon might be 60 million years older than we previously thought, which is pretty cool!

    Also, I find it nice to look at a geologic timescale and you can see all of the periods, epochs, ages, etc. and get a really nice idea of how things are laid out in Earth’s long history!


  3. Hi Robert, great question indeed! and thanks to all the other scientists for the replies, I am also learning a lot in this conversation.


  4. Hi Robert:
    Yes, the Earth formed approximately 4.6 billions of years ago. We know it based on the decay of radioactive isotopes on rocks from the continents (Australia for example), meteorites, and the Moon. And that is also the age of the Solar System as the planets were formed at the same time.


  5. Hi Robert,

    The earth formed approximately 4.6 billion years ago. The other scientists have provided great answers to the question, which I learnt from, since I never really researched in depth this area.

    So, thank you for asking this question, I got to learn as well! 🙂