A Moon as Old as Earth? Almost!

Earth is estimated to be 4.543 billion years old, and it's believed our Moon was born from a violent collision between the newly formed Earth and another young Mars-sized protoplanet dubbed Theia not long thereafter. But how long was "not long?"

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Until recently, the estimated age of lunar formation was 4.35 billion years ago, and folks who cling to that age are considered "youngMoon" advocates.