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The Moon's Mystery: Scientists Debate How it Formed

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#1 Crisp

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Posted 15 July 2013 - 09:39

The Moon's Mystery: Scientists Debate How it Formed

How was our planet's satellite formed? Scientists are still searching for the answer.

moon-formation-theories-debated_69202_60

This illustration of the moon being formed appears on the July cover of National Geographic magazine.

Illustration by Dana Berry, National Geographic

 

Before the giant impact model gained traction nearly four decades ago, three other models were in contention. One said the moon condensed from the same whirling cloud of dust that created Earth. But this "binary" model couldn't explain why the moon, far from being a smaller twin of Earth, is much less dense than our planet, with no iron core.

A second model held that the young molten Earth spun so rapidly that it split apart, flinging a giant blob of magma into space. But Earth's spin today and the moon's orbit don't fit the pattern predicted by the "fission" model.

In the third model, Earth's gravity lassoed the moon as it wandered through from some distant part of the solar system. This "capture" scenario was appealing until the Apollo astronauts brought their moon rocks back home. The minerals in them turned out to be similar to those in Earth's mantle—not exotic at all.

The giant impact model avoided all these problems. When it came along in the 1970s, the model fit an emerging view of how the solar system as a whole had formed. In that view, gaseous and rocky protoplanets grew within a disk around the young sun, competing for space, for tens of millions of years. Collisions were inevitable.

As Earth got bigger, it absorbed several Mercury-size or Mars-size objects. The final major blow was an impact so fierce that it left a permanent reminder in orbit around us. According to the impact model, the moon coalesced mostly from the shattered debris of the impactor, a rocky protoplanet similar to Earth. Because the impactor's own iron core sank into Earth's core, the moon is all rock.

 

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#2 Nick H.

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Posted 15 July 2013 - 10:08

Wow. I had only really heard of the capture scenario and assumed that to be how it had happened. I didn't realise the Apollo mission made it doubtful. Thanks for the information! (Y)

#3 +Aheer.R.S.

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Posted 15 July 2013 - 10:13

Ok silly question time..

If the moon is indeed all rock, how is it orbiting the Earth?

(There must be some elements within it that are effected by gravity, as it has it's own)



#4 Nick H.

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Posted 15 July 2013 - 10:18

Ok silly question time..
If the moon is indeed all rock, how is it orbiting the Earth?
(There must be some elements within it that are effected by gravity, as it has it's own)

Understanding orbits. The moon's orbit is affected by the Earth's gravity. All objects are affected by gravity. That's my incredibly basic understanding of it, anyway.

#5 +Aheer.R.S.

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Posted 15 July 2013 - 10:24

~snip~

No, sorry, I should have been clearer,

I have a basic understanding of Newton's law, what I meant was, if it is indeed all rock, then how come it has it's own gravity, as well as being able to orbit the Earth?

There must be something at the core of the moon to give it gravity, even if not iron..



#6 Stebet

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Posted 15 July 2013 - 10:37

No, sorry, I should have been clearer,

I have a basic understanding of Newton's law, what I meant was, if it is indeed all rock, then how come it has it's own gravity, as well as being able to orbit the Earth?

There must be something at the core of the moon to give it gravity, even if not iron..

 

Gravity is dictated by the mass and distance between two objects. Everything therefore causes gravitational pull if it has some mass, even you. Your own mass is just so cosmically small that the force exerted is hardly measurable. The moon, given it's size has some gravity, and it's because of that gravity (and the suns) for example that we have ocean tides for example :)

http://en.wikipedia....sal_gravitation



#7 +Phouchg

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Posted 15 July 2013 - 10:38

Fundamental forces says that all matter has gravity. However, it is the weakest force of all (many orders of magnitude), so unless the object in question is very large to compensate the difference, it is being overcome by other forces and interactions.

 

Ok, ninja'd... well done, Stebet (Y)



#8 Nick H.

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Posted 15 July 2013 - 10:40

Gravity is dictated by the mass and distance between two objects. Everything therefore causes gravitational pull if it has some mass, even you. Your own mass is just so cosmically small that the force exerted is hardly measurable. The moon, given it's size has some gravity, and it's because of that gravity (and the suns) for example that we have ocean tides for example :)

Thank you. I was trying to find a way to write that when I realised what the question was. :laugh:

#9 Solid Knight

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Posted 15 July 2013 - 10:59

You scientists amuse me. Everyone knows that God made it. Seriously, something crashed into Earth? How? It doesn't have any wheels!



#10 Dutchie64

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Posted 15 July 2013 - 11:08

you so funny..... :-\



#11 +-T-

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Posted 15 July 2013 - 11:15

I had never heard of those three alternatives, I'd always just accepted the impact theory

#12 sagum

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Posted 15 July 2013 - 11:23

I had never heard of those three alternatives, I'd always just accepted the impact theory

 

 

Your mind will be blown when you hear about the alien theory :) hauled in by the aliens so they could hide behind it and monitor us for millenniums... have you ever seen the other side of the moon? nope, they have alien moon bases and spaceships docked there!

 

Or, the theory that the moon doesn't even exist



#13 +Phouchg

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Posted 15 July 2013 - 11:25

Your mind will be blown when you hear about the alien theory :) hauled in by the aliens so they could hide behind it and monitor us for millenniums... have you ever seen the other side of the moon? nope, they have alien moon bases and spaceships docked there!

 

Or, the theory that the moon doesn't even exist

 

Nazi aliens, you mean?



#14 Praetor

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Posted 15 July 2013 - 11:42

Or, the theory that the moon doesn't even exist

 

LMAO that site is so absurd that it's so funny!



#15 FloatingFatMan

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Posted 15 July 2013 - 11:51

You scientists amuse me. Everyone knows that God made it. Seriously, something crashed into Earth? How? It doesn't have any wheels!


Yeah! God had a bogey in his nose, so he picked it, rolled it and flicked it! :p



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