So how old is planet Earth today?

[Duckshot]

How old is planet earth thought to be today, and how has the presumed age of Our planet evolved in the last fifty years or so?

When I was in grade school the claim was 12-1/2 billion years or so. Seems we gained a couple billion years in the last half century...

 

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[DizzyDigger]

12.5 billion is close to age of the Universe itself, as it has been calculated
to be roughly 13.8 billion years old.

The Earth and our Solar System is considered to be about 4.5 Billion years old.

 

[Swaveab]

I couldn't tell you, but do you plan on throwing it a birthday party?

 

[newnan man]

I wonder how they come up with those figures & is the scientific community on board? Smarter people than myself that's for sure.

 

[DizzyDigger]

I wonder how they come up with those figures & is the
scientific community on board? Smarter people than myself that's for sure.

Those would be the commonly accepted numbers within the scientific community.

These folks can explain it far better than I can:

https://www.popsci.com/story/science/how-old-is-the-universe/

 

[Charlie P. (NY)]

Depends at what point you consider a planet "born". It was a ring of material orbiting the Sun that separated into what accreted and compressed into the current planets; though at least one appears to have failed and become the asteroid belt.

DizzyDigger's 4.5 billion years is the age we can tell the molten planet was basically sable enough to start cooling. 4.4 billion years ago it is thought something smacked the Earth and that is what led to the formation of our single moon.

How do they come up with the age? Once molten rock crystalizes the isotopes in it start to decay at known rates. Some, like Rubidium 87 have a VERY long half life. In the order of 49,000,000,000 years. Rb 86 has a half-life of days so that decays rapidly. But Rubidium 85 is stable. So if you compare the amount of Rb 87 to the amount of Rb 85 in a matrix you can estimate the age of the sample.

https://en.wikipedia.org/wiki/Oldest_dated_rocks

 

[jeff of pa]

approximately 65 years 5 months 28 days old according to my calculations.

the rest is all conjecture and taking other peoples word for it

 

[Red-Coat]

The generally accepted estimate for the age of Earth is 4.54 ± 0.05 billion years. However, as already said, planetary formation is an evolutionary process over a period of time and this date probably corresponds to the accretion/core formation of the nebular material from which Earth as we know it evolved.

We don’t rely completely on isotopic analysis of the materials available to us on Earth. Most samples are unable to give us a direct date for formation because our Earth has undergone subsequent differentiation into core, mantle and crust followed by mixing and unmxing through plate tectonics, weathering and hydrothermal circulation

Those processes can skew isotopic dating mechanisms, for which you need a ‘closed system’ where the parent or daughter nuclide (characterised by the number of neutrons and protons an atom contains) has been unaffected through time. Probably the closest we can come to that are samples of Archaean lead ore (galena) which are the earliest homogeneous lead-lead isotope systems that we know of on our planet. Those have returned dates of 4.54 billion years ± 1%

In addition to multiple sampling on Earth, we also use evidence from meteorites to corroborate our estimates. Certain meteorite types represent undifferentiated and pristine material from which the accreting solar disk was formed and consequently yield dates with higher degrees of scientific reliability.

The most primitive meteorites also help us to date the solar system itself. Some primitive carbonaceous meteorites contain what are known as ‘calcium–aluminium-rich inclusions’ (CAIs). These are the oldest known materials to have existed in solid form following the solar nebula that generated the building blocks for our planetary systems. We don’t have a huge amount of data but analyses so far have given a weighted mean age for CAIs of 4.567.30 billion years ± 0.004% and that’s currently taken to be the age of our Solar System prior to planetary accretion.

 

[Duckshot]

approximately 65 years 5 months 28 days old according to my calculations.

the rest is all conjecture and taking other peoples word for it

That's actually a good answer IMO, so long as you don't get caught up is solipsism.

The thing is a million years is long time. A billion is a thousand million.

I found an intersting article on dark matter, in ScientificAmerican iirc. The recent data collected suggest that the therory of relativity needs tweaking.

There are a bunch of assumptions made in the estimates of age from radiologic dating. One of these is that the physics found on earth is constant throughout both galaxy. Another is that decay of isotopes is constant over enormous spans of time. Kind of arrogant assumptions IMO. The estimate might be correct. But it could be totally wrong.

 

[Charlie P. (NY)]

And the beauty of science is that whatever solution is best supported will be the revised version.

We have no evidence that physics and natural law is a local phenomena so it's a safe bet it works through-out our solar system, if not this whole spiral-arm region of the galaxy. Nearer the galactic core - all bets are off until we get more data and that's where the elegant theories start filling in.

Astonishingly Voyager 1 (launched in 1977) is still transmitting data back to Earth. New info this month on interstellar density fluctuations in the "vacuum" of space. Its the furthest we have physically probed away from "home". Just over 14 billion miles away and still going.

The nearest non-solar orbit planet is 24,900,000,000,000 miles away (Proxima Centauri). So, if Voyager 1 was headed that way it would take 78,257 years (assuming no deceleration) to reach our nearest neighbor.

Kind of sad we'll likely never leave our solar-system . . . unless someone figures how to achieve and survive alternative travel methods.

 

[Tony in SC]

A young couple came out to the farm the other day. When they were leaving the lady said I love your place have you lived here all your life? My answer was. "I don't know yet".

approximately 65 years 5 months 28 days old according to my calculations.

the rest is all conjecture and taking other peoples word for it

 

[Duckshot]

"Oh", she says. "Can we have it when you leave?"

 

[Trezurehunter]

If those numbers are true, then I feel like I'm as old as Planet Earth !

 

[TooManyHobbies]

approximately 65 years 5 months 28 days old according to my calculations.

the rest is all conjecture and taking other peoples word for it

Then it's at least 10 years older than I can confirm.

 

[Clad2Silver]

What difference does it make?