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  #11  
Old 13th March 2015, 05:26 PM
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Default Re: How do we know the age of the Earth?

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STOKER said View Post
By all means Cirrusly, it's all yours.
Thanks, Stoker. I didn't mean to sound as though I understood what you said. I (mostly) don't but what you wrote has interested me and has started a conversation between me and my partner who's dug out an old textbook 'The World of Radioisotopes'. And we're both on a learning curve. Exciting. Thank you!
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  #12  
Old 21st August 2015, 12:35 AM
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Default Re: How do we know the age of the Earth?

Actually, although the method given above is most commonly used to date rocks on earth, it is not through dating of terrestrial rocks we know the age of the earth. Some of the oldest minerals on the face of the planet have been found as zircons in Western Australia and these zircons have been dated at about 4.04 billion years old. However, it is by dating the Lead 207/Lead 206 system in meteorites that we can work out the age of the earth. This, when first done in 1956 (by Claire Patterson) was given as 4.55 billion years. With improvements in the understanding of decay constants, it has been revised to about 4.54 billion years old.
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  #13  
Old 24th October 2015, 07:10 AM
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Default Re: How do we know the age of the Earth?

Count the candles on its birthday cake!

Actually just wanted to drop this link outlining the history of our understanding of this topic:

http://www.scientificamerican.com/ar...-of-the-earth/
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  #14  
Old 24th October 2015, 10:30 PM
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Default Re: How do we know the age of the Earth?

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Spearthrower said View Post
Count the candles on its birthday cake!

Actually just wanted to drop this link outlining the history of our understanding of this topic:

http://www.scientificamerican.com/ar...-of-the-earth/
Cool! Thanks.

That and this thread triggered me to post a new excerpt from my How do we know? collection on my Bleeding Edge blog. It looks at the even bigger question of how we determine age of the Earth, stars and universe. Some might find it useful and there are links/references included which go into much greater depth than the short piece itself.

http://kennyachaffin.blogspot.com/20...nd-age-of.html
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  #15  
Old 25th October 2015, 02:41 AM
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Default Re: How do we know the age of the Earth?

Nice write-up!
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  #16  
Old 25th October 2015, 02:59 AM
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Default Re: How do we know the age of the Earth?

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Spearthrower said View Post
Nice write-up!
Thanks!

Very short and hopefully concise. Intended for a interested non-scientist audience.
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  #17  
Old 25th October 2015, 09:31 AM
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Default Re: How do we know the age of the Earth?

One of the most comprehensive sources from the perspective of radioisotopes, by the famous Blue Flutterby:

Cali: Radiometric Dating Is Rigorous
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  #18  
Old 25th October 2015, 11:33 AM
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Default Re: How do we know the age of the Earth?

this is why we call her mother earth... she's a woman, you'll probably never know her real age
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  #19  
Old 25th October 2015, 11:41 AM
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Default Re: How do we know the age of the Earth?

I suspect we will. The error bars are shrinking all the time. There's very little uncertainty left, as the above linked post shows quite clearly, even though the bars have been significantly reduced in the 6 or 7 years since that post was originally made.

Besides, you can tell the age of a woman to a first approximation quite easily if you know what to look at. Elbows are the best indicator.
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  #20  
Old 25th October 2015, 02:35 PM
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Default Re: How do we know the age of the Earth?

Lots of interesting things indicated by studying zircons ( minor aside). The possible age of life as been put back 300 milloion years recently from studying carbon detected in zircons from WA.
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UCLA said
The researchers, led by Elizabeth Bell — a postdoctoral scholar in Harrison’s laboratory — studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules.

The scientists identified 656 zircons containing dark specks that could be revealing and closely analyzed 79 of them with Raman spectroscopy, a technique that shows the molecular and chemical structure of ancient microorganisms in three dimensions.

Bell and Boehnke, who have pioneered chemical and mineralogical tests to determine the condition of ancient zircons, were searching for carbon, the key component for life.

One of the 79 zircons contained graphite — pure carbon — in two locations.

“The first time that the graphite ever got exposed in the last 4.1 billion years is when Beth Ann and Patrick made the measurements this year,” Harrison said.

How confident are they that their zircon represents 4.1 billion-year-old graphite?

“Very confident,” Harrison said. “There is no better case of a primary inclusion in a mineral ever documented, and nobody has offered a plausible alternative explanation for graphite of non-biological origin into a zircon.”
Full article
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Last edited by AUSloth; 25th October 2015 at 02:36 PM.
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