How do we know the age of the Earth? (video)

WASHINGTON, Oct. 23, 2017 — The Earth is 4.565 billion years old, give or take a few million years. How do scientists know that? Since there’s no “established in” plaque stuck in a cliff somewhere,  geologists deduced the age of the Earth thanks to a handful of radioactive elements. With radiometric dating, scientists can put an age on really old rocks — and even good old Mother Earth. For the 30th anniversary of National Chemistry Week, this edition of Reactions describes how scientists date rocks: https://youtu.be/7cFYPYaD4zQ.

Reactions is a video series produced by the American Chemical Society and PBS Digital Studios. Subscribe to Reactions at http://bit.ly/ACSReactions and follow us on Twitter @ACSReactions.

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