How old is the moon?

Old moon?: The moon cooled to a solid 4.4 billion years ago.
Old moon?: The moon cooled to a solid 4.4 billion years ago.Courtesy ViaMoi

Where did the moon come from?

Scientific studies indicate the solar system formed about 4.6 billion years ago and that about 4.5 billion years ago an object about the size of Mars hit the Earth, blasting away material that eventually cooled into what is now our moon. (Read more in Science News: "The Solar sytem's big bang")

How do we know the moon's age?

Rocks brought back from the moon contain zircon crystals. Zircons crystallize only after 80 to 85 percent of a volume of molten rock has solidified. By understanding how uranium within the zirconium breaks down into lead, scientists believe they know when the crystals formed with an error margin of less than 4 million years. The oldest zircons from the moon are about 10 million years older than the oldest yet discovered on Earth. The ages of lunar zircons identified in other studies hint that small amounts of the moon’s crust remained molten for another 200 million to 400 million years.

"Alexander Nemchin and his colleagues have used a uranium-lead dating technique to scrutinize a 0.5-millimeter-wide zircon embedded in a moon rock collected by Apollo 17 astronauts in December 1972. The crystal — which, although small, is rather large as zircons go — is about 4.417 billion years old, the researchers report online January 25 in Nature Geoscience."

Science News: "Oldest zircon fine-tunes history of moon's formation"

Your rating: None Average: 3.7 (15 votes)
Your rating: None Average: 3.7 (15 votes)

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

the moon is older then the acuall earth :] because a astroid came into the earth and hear wee are now :]]

posted on Thu, 02/19/2009 - 10:34pm
tippy's picture
tippy says:

i think 99,000000000000000000000000000000000000000000000000000000 BC years old

posted on Sun, 02/22/2009 - 11:14am
Anonymous's picture
Anonymous says:

That Isn't Actually How The Earth Really Started.

posted on Wed, 01/26/2011 - 3:00pm
Candace's picture
Candace says:

are moon rocks heavy or lite?

posted on Tue, 02/24/2009 - 10:05pm
ARTiFactor's picture
ARTiFactor says:

They are the same as the Earth's crust because that is where they came from.

posted on Wed, 02/25/2009 - 8:12am
Lawrence the chicken farmer's picture
Lawrence the chicken farmer says:

If space dust is a constant?
Why can't sience detuman the age of the moon ,by how much dust is on the surface??

posted on Sun, 05/17/2009 - 10:25pm
ARTiFactor's picture
ARTiFactor says:

Nice idea but the dust is always disturbed by meteor impacts. A better technique is to use half-life properties of radioactive dirt which was done and showed the moon to have cooled about the same time as the Earth.

posted on Mon, 05/18/2009 - 10:17am
Eponymous's picture
Eponymous says:

So by evolution and expansion, the earth gave birth to the moon.
So romantic!

posted on Thu, 05/21/2009 - 4:03pm
ARTiFactor's picture
ARTiFactor says:

When something the size of Mars smacks Earth hard enough to break off a chuck the size of the moon I would not call it evolution, expansion, or romantic!

posted on Thu, 05/21/2009 - 5:59pm
Anonymous's picture
Anonymous says:

could our water have come from this combination of earth and now moon? does the time scale match?

posted on Sun, 06/07/2009 - 12:43pm
ARTiFactor's picture
ARTiFactor says:

To learn about the origin of Earth's water click this link.
Origin of water on Earth

posted on Mon, 06/08/2009 - 7:25am
justine's picture
justine says:

awhh i know what is the age of our moon for now, well it means i don't have to make my mind worst

posted on Wed, 06/30/2010 - 3:46am
eebee's picture
eebee says:

Wouldn't something the size of the moon destroy the Earth on impact?

posted on Mon, 07/19/2010 - 5:21pm
ARTiFactor's picture
ARTiFactor says:

Yes, I think it would. The molten debris would split into two globs that would then cool to become Earth and Moon.

posted on Tue, 07/20/2010 - 9:28am
astronomy's picture
astronomy says:

yes it would the debris off the astroid and the melted iron rock would split the earth into 2 globes

posted on Mon, 10/11/2010 - 9:09am
Anonymous's picture
Anonymous says:

so then 'artifactor' it is your contention (and the rest of the establishment using your hypothesis) that the perfectly spherical shape of the moon and earth after this alleged collision is the result of 4 billion years of uni-planar rotation/spinning with no more than a 23 degree variance/wobble?

that would give us a cylindrical shape even if the impact meant that the strating morphology were at best an icosahedron.

try again.

posted on Fri, 09/24/2010 - 2:41pm
JGordon's picture
JGordon says:

Whoa! Those are a lot of fancy words! I'm not sure I follow—why would the Earth have been an icosahedron?

I'll let Art handle this, but here are a couple thoughts I had: the Earth actually isn't a perfect sphere, is it? As I understand it, it's sort of a slightly squashed sphere shape. Also, I was under the impression that the spherical (or mostly-spherical) shape of planetary bodies wasn't totally determined by their rotation, but by their mass—that's why big (but not super big) things like asteroids remain chunky and uneven, while objects approaching the size of a planet or moon sort of pull themselves into a ball (because of their own gravity).

What's your explanation, boss? ("Try again" is oh so sassy, but not so illuminating.)

posted on Fri, 09/24/2010 - 3:56pm
ARTiFactor's picture
ARTiFactor says:

The universe is full of spheres, not cylinders nor icosahedrons.. As JGordon says, large heavenly bodies become spheres because of gravity.

posted on Fri, 09/24/2010 - 8:31pm
RobotScientist's picture
RobotScientist says:

Neither earth or the moon is perfectly spherical. Each is slightly ovoid, the direct result of such a collision and slow reshaping from gravity pushing down on it from millenia

posted on Fri, 01/31/2014 - 5:25pm
Anonymous's picture
Anonymous says:

are moon rocks heavyer than earth rocks or r they the same weight?

posted on Sun, 10/10/2010 - 9:34pm
astronomy's picture
astronomy says:

i think moon rocks r the same weight not 100% sure

posted on Mon, 10/11/2010 - 12:15pm
astronomy's picture
astronomy says:

meteor shower this month 21 and 22 u will b able to c 20 meteors per hour

posted on Wed, 10/13/2010 - 6:58pm
Anonymous's picture
Anonymous says:

how big was earth before the astroid hit it

posted on Wed, 11/10/2010 - 9:31am
astronomy's picture
astronomy says:

things were alot different before the astroid hit the oxygen levels were different the atmosphere was different butt i think Earth Was The same size as it is now .

posted on Thu, 11/18/2010 - 8:38pm
Anonymous's picture
Anonymous says:

The reptilians drove the moon into our orbit before colonizing this planet around 800,000 B.C.

posted on Wed, 11/17/2010 - 2:48am
astronomy's picture
astronomy says:

a large astroid from the astroid belt collided with another astroid causing it to go off course and into the earths orbit. thats how the earth was destroyed

posted on Wed, 11/17/2010 - 7:47pm
astronomy's picture
astronomy says:

large meteor shower tonite and the 18th

posted on Wed, 11/17/2010 - 7:52pm
Anonymous's picture
Anonymous says:

what are meteorites

posted on Wed, 11/17/2010 - 8:56pm
astronomy's picture
astronomy says:

meteorites are pieces of nickel iron rock most meteorites come from the astroid belt

posted on Thu, 11/18/2010 - 3:22pm
Anonymous's picture
Anonymous says:

astronomy. what are carbonoxious chondrites made of?

posted on Sun, 01/02/2011 - 6:48pm
astronomy's picture
astronomy says:

carbonaxiouse chondrites are made of carbon and silica inclusions. ps meteor shower tonite a tomorrow.

posted on Mon, 01/03/2011 - 6:52pm
Lukas's picture
Lukas says:

Dont take that crap. Moon is a lot older than earth and most likely has been brought here from different solar system. It will all come out soon. Just watch.

posted on Fri, 01/21/2011 - 11:48am
tarani's picture
tarani says:

If earth is 4 billion yrs old then life has probably been wiped out a few times then reinvented. So its a good chance that if life were to have existed uninterupted for say a billion years then it would have evolved to a level where it might have eradicated ageing and maybe even left earth to aviod extinction because of climate change or a meteorite.So maybe the green men in flying saucers are actually a form of us that left earth 2-3 billion yrs ago ?

posted on Sun, 03/04/2012 - 3:16pm
Star Lolli's picture
Star Lolli says:

The moon is 4.5 billion years old. You guys are wrong!

posted on Tue, 03/06/2012 - 10:41am
Anonymous's picture
Anonymous says:

5.3 billion years old, all u sheep should listen to Never A Straight Answer more often, makes me look better.

posted on Sat, 05/05/2012 - 11:08pm
Anonymous's picture
Anonymous says:

what if the earth is only 6k years old and th mon was formed at the same time as the earth

posted on Mon, 05/07/2012 - 2:06pm
The buzz's picture
The buzz says:

does pot make oxgen if so can we use it to teraform mars????

posted on Wed, 08/08/2012 - 9:39pm
Anonymous's picture
Anonymous says:

This is stupid. Meteoric dust falls constantly on to the moon. When the Apollo astronauts landed on the moon, scientists thought that Neil Armstrong would sink into the many feet of dust on it from the constant fall of the dust. As we all know, he didn't; there was only about an eighth of an inch of dust on the moon. If you extrapolate the amount of dust on the moon with constant fall, you will find that it is only a few thousand years old. This disproves your age and argument on the moon unless you want to add a few "epicycles" in there if you know what I mean.

posted on Fri, 02/08/2013 - 10:18pm
mdr's picture
mdr says:

Your old "meteoric dust argument" does not hold up under scrutiny, as explained here.

posted on Mon, 02/11/2013 - 2:52pm
rosie's picture
rosie says:

how do we know how old the moon is??

posted on Sat, 04/19/2014 - 3:56am

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