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How did Earths Moon come to be?


LukeSkywatcher
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Seems that every few weeks " scientists " are having to rethink some theory or other in light of new information so can't take anything for granted.

Not a bad thing except for those entrenched in their own pet theory :grin:

You've only got to watch some old Sky at Night programs to see scientists claiming with some certainty that calculations support a theory only for it to turn out to be wrong a few years later.

Dave

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Personally I think the best we will ever be able to say about the moons formation will be to say that <insert latestest current theory> is the most likely way that the moon was formed. I think the mechanics of looking back in time to say for definite that a certain formational theory is 100% correct will be extremely hard to do. In truth it may also be that moons can form in a multitude of ways, rather than just one. 

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It's highly likely that two objects of similar composition, close together, formed from the same proto material. As gravity attracts smaller items together to form planets, minor planets, asteroids etc, then is it not possible two or more objects could form from the same material in the same orbit? 

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In the early Solar System stuff was continually accreting and smashing into each other, forming and reforming until it all settled down into some semblance of order after a few million years and then promptly started again with planets migrating around causing more chaos until we arrive at a time when we can observe what is, in cosmic terms, a short interlude in the history of the Solar System a few more billion years and it will all be gone again.

If observations of exoplanets have shown us anything it's that there is no such thing as a typical planetary system so ours and us may well be unique.

Dave

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On 24/08/2018 at 12:23, goodricke1 said:

Well I wish it had never came to be, it's nothing but a bloody nuisance!!

Without the Moon you would not be here to complain about it! It stabilizes the Earth, and without it the tilt of the Earth would move to extremes, where one hemisphere would scorch while the other would freeze. It influences the tides, the winds and many of the life forms living in our ocean's. It influences me to get off by rear and go and observe it. Without the Moon human life on this planet would not be able to survive! I'm glad we've got the Moon, I'm just sorry it isn't there every night.

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I should just pass on but reading so many replies i'll make this post but no more . I'm not educated pass H.S.  , but I've heard so many thoughts and answers over my lifetime and  i'm one that doesn't believe in the Big Bang theory and that's why I won't continue to post but I will leave a couple questions and read what anyone post but I won't reply , sorry . Don't want to get in trouble . But honestly I know about magnetic fields how they draw objects to them but always with no shape or perfect form . I also know that all planets have perfect round form as seen in space as earth does seen from the moon or anywhere else in space but also we see those planets and the sun in telescopes and what we see and project are perfectly round . Other than planets every object in space is without perfect form or shape except stars which we take for granted are like our sun at a distance which our sun we know is round so we take it that stars are also round but since  we have no magnification strong enough to get as close to a star as we are to our sun  we really don't have perfect proof that stars are round . Now if i'm wrong please feel free to set me right with proof . Don't worry , i'll not get upset at all , just curious as to what you think and proof  . 

Now that I got that out of the way let me mention this and then i'll ask my main question . We know asteroids , comets and other objects in space they are traveling through space none are perfectly round , at least all pictures I have seen taken by the Hubble or other telescopes that are on the web none are round , all are odd shaped with no form . Now we all know also that here on earth if you take any object on earth and blow it up , it shatters into many large and small pieces but none of those pieces have shape or form or related sizes . 

QUESTIONS  : If  there was such a thing as the Big Bang and matter as we know it was shattered and spread through out the Universe as we know it , How was that matter created to start with and the energy that caused it to created the Big Bang  ??  Second is if there was a Big Bang and matter as we know it was scattered all over the Universe as we know it different sizes , different shapes with no form , WHAT caused just certain matter to become formed and shaped as a round ball as we know here on earth ?? WHY didn't every single piece of that beginning matter take perfect shape and form as a round ball also ??

I know some answers would be because with so much matter being projected from a source of center which in my mind would have to be magnified gravity to hold it together to start with , as matter traveled through out space ran into each other but how do you know that for sure and why did only some matter take perfect shape and form into round like balls which we know as our Sun , Earth , Moon and other planets in the Solar System ?? Why didn't every piece of matter shape perfectly round ?? 

Remember i'm not posting this to make anyone upset or angry at me and I don't want to cause a problem and that's why i'll read any replies but to not cause problems forgive me but I bow out to reply . 

 

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3 hours ago, Mr Spock said:

It's highly likely that two objects of similar composition, close together, formed from the same proto material. As gravity attracts smaller items together to form planets, minor planets, asteroids etc, then is it not possible two or more objects could form from the same material in the same orbit? 

I'd think it's certainly possible, but in the case of the Earth and Moon I believe there is evidence to suggest that this is less likely to have been the case.  My recollection is that the evidence is most probably explained by the two bodies being formed from the same molten material at the same time.  I think I've about exhausted what I can remember now though.

James

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Ah well, this all leads on to philosophy and religion and we can't discuss the latter...  The former is likely to make the ol' brain explode!!!

Edited by Gina
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Sadly (at least for science) all things that happened before the Big Bang (if the Big Bang theory is correct) is unknowable as this lies outside the realm of the actual universe. As Gina says science here can only guess (hence we get the multiverse, branes and a whole host of other exotic theories etc), so here lies the crux of the dilemma; how can we know something we cannot gleam any information about? Science then treads into philosophy, at which point it breaks down and holds no scientific value whatsoever as it in the end becomes just pure speculation.

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RonL, from what you've written I wonder if you have perhaps misunderstood some of the ideas in the Big Bang.  It's probably not a great name for what cosmologists believe happened and in fact was coined as a perhaps derogatory term by Fred Hoyle who didn't accept the idea and preferred the concept of a "steady state" universe.

To start with, it is not believed that matter existed when the process started and that atoms of hydrogen didn't even start to form until about 400,000 years afterwards.  It's probably also misleading to think of the event as having a "centre" from which matter spread out.  It's a tough one to explain however :)  Sometimes I find it helps to think of it not as matter spreading outwards, but as more space coming into existence between the matter, though I'm not going to claim that's any more accurate.

As regards what causes objects such as the Earth to become round, it's gravity, basically.  Beyond a certain size/mass the gravitational interaction within the body tends to force it into a roughly spherical shape.  On Earth for example, if a mountain or mountain range becomes too massive it can actually sink into the crust, effectively preventing the planet from being less spherical.  Below that limit on size, objects can be pretty much any shape.

James

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1 hour ago, celestron8g8 said:

i'm one that doesn't believe in the Big Bang theory

As said there was theoretically nothing before the "Big Bang" a misleading name as James said not helped by CG images in documentaries showing an explosion,

There was no space, no time, no nothing, then it was all created over a considerable time but brief in cosmological terms, can't remember the numbers but not instantaneous.

Bearing in mind there was theoretically not so much as an atom of hydrogen around and no laws of physics it could all expand faster than the speed of light as there was no light.

All this is based on running the creation movie backwards to nothing so difficult to believe though there is science to back it up, equations that I don't understand so you can believe it or not Ron you're prerogative and we won't think any less of you :grin:

Dave

Mr Einsteins famous equation states that pure energy can create matter so enough energy could create the Universe

Edited by Davey-T
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4 hours ago, celestron8g8 said:

I should just pass on but reading so many replies i'll make this post but no more . I'm not educated pass H.S.  , but I've heard so many thoughts and answers over my lifetime and  i'm one that doesn't believe in the Big Bang theory and that's why I won't continue to post but I will leave a couple questions and read what anyone post but I won't reply , sorry . Don't want to get in trouble . But honestly I know about magnetic fields how they draw objects to them but always with no shape or perfect form .

The most complicated and beautiful shapes arise! Have a look here: https://www.google.nl/search?q=ferrofluids&amp;newwindow=1&amp;client=opera&amp;hs=GbP&amp;source=lnms&amp;tbm=isch&amp;sa=X&amp;ved=0ahUKEwixwfbR9I3dAhUSLFAKHZ5bDrEQ_AUICigB&amp;biw=2105&amp;bih=1239

I also know that all planets have perfect round form

They don't. They are oblate ellipsoids, and that only by approximation. 

as seen in space as earth does seen from the moon or anywhere else in space but also we see those planets and the sun in telescopes and what we see and project are perfectly round . Other than planets every object in space is without perfect form or shape except stars which we take for granted are like our sun at a distance which our sun we know is round so we take it that stars are also round but since  we have no magnification strong enough to get as close to a star as we are to our sun  we really don't have perfect proof that stars are round .

How about these actual images of round stars: https://en.wikipedia.org/wiki/List_of_stars_with_resolved_images
If you took the trouble you'd find many more.

Now if i'm wrong please feel free to set me right with proof . Don't worry , i'll not get upset at all , just curious as to what you think and proof  . 

 

Quote

Now that I got that out of the way let me mention this and then i'll ask my main question . We know asteroids , comets and other objects in space they are traveling through space none are perfectly round , at least all pictures I have seen taken by the Hubble or other telescopes that are on the web none are round , all are odd shaped with no form . Now we all know also that here on earth if you take any object on earth and blow it up , it shatters into many large and small pieces but none of those pieces have shape or form or related sizes . 

How about compressing objects down to a ball, like a crumbling a sheet of paper? Why think of blowing things up?

QUESTIONS  : If  there was such a thing as the Big Bang and matter as we know it was shattered and spread through out the Universe as we know it ,

Matter was not spread around. The big bang was everywhere. It involved the entire universe. Everything started fleeing from everything else.

How was that matter created to start with and the energy that caused it to created the Big Bang  ?? 

The big bang theory does not discuss this. It only deals with the development of the universe after the first Planck era. We have no idea what came before. 

Second is if there was a Big Bang and matter as we know it was scattered all over the Universe as we know

No such thing is suggested by the Big Bang theory.

it different sizes , different shapes with no form , WHAT caused just certain matter to become formed and shaped as a round ball as we know here on earth ?? WHY didn't every single piece of that beginning matter take perfect shape and form as a round ball also ??

Only in mathematics do perfect spheres exist, but gravity attracts and gravity does the job.

I know some answers would be because with so much matter being projected from a source of center which in my mind would have to be magnified gravity to hold it together to start with , as matter traveled through out space ran into each other

Matter accretes all the time. 

but how do you know that for sure

It shows in our pictures. Look a the Eagle nebula photographed by Hubble (and our members here). Lot's of globules in the Orion nebula too. Those are collapsing blobs of gas.

and why did only some matter take perfect shape and form into round like balls

None did. The roundest object in the solar system is the Sun, and even that is an oblate ellipsoid. The more massive an object, the better it will resemble an ellipsoid. A gaseous mass which does not rotate would end up very, very close to a sphere though.

which we know as our Sun , Earth , Moon and other planets in the Solar System ?? Why didn't every piece of matter shape perfectly round ?? 

Remember i'm not posting this to make anyone upset or angry at me and I don't want to cause a problem and that's why i'll read any replies but to not cause problems forgive me but I bow out to reply . 

 

Would you believe, we don't 'believe' in the Big Bang. It's just part of our best model for explaining the state of the universe.

Science, by the way,  is not a body of knowledge: it's a method. Some of us take part in it, others take note of it and follow it. Science can expand our knowledge like no other method can. That's why we find it so interesting.

In science the goal not to prove what we know. Every hypothesis is tested over and over again in as many ways as we can think of. Every prediction that follows from the hypothesis is checked out.

Only if a hypothesis survives this onslaught it becomes accepted as a theory. Of course, we always hope for a better idea to come along, so that we may end up with a better theory. Our knowledge is never complete.

To date, the Big Bang is the best theory that describes the development of the universe.

And since the 1980s (starting with Betelgeuse)  we have been able to resolve the disks of stars.

Edited by Ruud
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On 24/08/2018 at 03:20, SIDO said:

Aren't alot of comets, planets asteroids and dwarfs planets of similar geologic makup as earth and as well origin. If the whole asteroid belt was once 5 Rocky planets they must have had similar geological makups/origins as well/questions?

I don't think 5 planets formed the asteroid belt. The Moon has more mass than all the asteroids combined.

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13 hours ago, Gina said:

But where did the energy come from?  It's alright - I'll go back to sleep now..............

Energy has always existed, as it cannot be created or destroyed. The real big question is "what made it go BANG!" Or Fizz or Pffftt, or whatever? I know, but I'm not allowed to tell!

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1 hour ago, mikeDnight said:

Energy has always existed, as it cannot be created or destroyed. The real big question is "what made it go BANG!" Or Fizz or Pffftt, or whatever? I know, but I'm not allowed to tell!

Matter - energy equivalence suggests that the total amount of energy and matter in the universe is constant, although it can be 'lost' inside black holes (only to emerge as Hawking radiation as the universe eventually heads for utter monotony.

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5 hours ago, mikeDnight said:

Energy has always existed, as it cannot be created or destroyed.

Uh oh! We are looking into that horrible thing that human brains can’t comprehend! Infinity! I don’t think it is as simple a statement as this though as saying that energy has always existed, as this law only becomes an immutable law (for want of a better word to describe it) within the confines of our own universe since the actual creation of the universe. We cannot extrapolate that this law has always been the same before the universe came into existence as again we cannot know through any direct measurements what conditions where before the so called Big Bang. Thorny issue I know which has occupied many a minds for centuries, and will continue to do so no doubt, but to be truly scientific we can only be certain of things that occur within our universe, and not anything outside of it, so we cannot really say that this energy which was needed to create the universe has always existed as we again get into the realm of supposition only and not evidence. 

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Before one gets too involved in the Physics/Maths etc. of the "Big Bang", there still seems
to a lot of "fun" to be had with study / predictions of n-body classical theories. One of the
initially (perhaps naively!) surprising things is that there are no *exact* solution for these... 

https://en.wikipedia.org/wiki/Stability_of_the_Solar_System (arguably not terribly stable!) ?

The availability of information on the configuration of external planetary systems (Hot
Jupiters whizzing around parent stars in days etc!) show that ours may be somewhat in
the minority with a "neat" structure of small rocky planets... asteroid belt... gas giants etc. ?

There is evidence for an exciting past in the Solar System and (perhaps daunting?) future! 
That science doesn't know (can't predict) *everything* doesn't mean "anything goes" etc. ?

Edited by Macavity
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