Scientist Explains How to Measure Actual Earth Age
- Pixabay/Steven Goddard
Using these methods, geologists have found minerals on Earth that date as far back as 4.4 billion years, meaning the planet has been around at least that long.Â
But if scientists say Earth is more than 4.5 billion years old, where did those extra 100 million years or so come from?
Earth, as mentioned, has changed a lot over billions of years, especially through processes such as plate tectonics, which shift the crust, birthing new land out of magma, and subducting old land back underground. As a result, rocks from the very beginning of the planet's history are hard to find; they've long since eroded or melted back into raw material.
Scientists can also use radiometric dating to determine the age of rocks from other parts of the solar system. Some meteorites contain material that is more than 4.56 billion years old, and rocks from the moon and Mars also date back about 4.5 billion years.
That's pretty close to when the solar system started forming, out of a cloud of gas and dust, around the newborn Sun. Knowing all these relative ages allows us to start building a timeline of how the Earth, Moon, Mars, and all the other tiny floating rocks came to be.
But the transition from ancient dust cloud to planet Earth didn't happen all at once, but over millions of years, according to Rebecca Fischer, an Earth and planetary scientist at Harvard University.
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