Traces of another world found on the Moon (BBC)

originally posted by: OccamsRazor04
Your figures are wrong.
402,336 km = Distance between the Moon and Earth
22,500 km = Original Distance
379,836 = 402,336 km - 22,500
3.78 cm = distance the Moon moves / year
3780000000 cm = Distance after 1 Billion years
378,000 km

You were right up until you converted cm to km, off by a factor of 10 there, should be 37,800km. While that's an accurate calculation, it's not the right number which I'll explain shortly.

originally posted by: OccamsRazor04
How is 22,000 KM touching?

Well if the moon is over 4 billion years old, then there's no way it could move 378,000 km per billion years for 4 billion years and be only 402,336 km away, so the math doesn't work. Even with the corrected conversion of 37,800 km, it doesn't add up to 402,336 km away after over 4 billion years.

So what's the solution?

As the moon is moving away, the Earth's rotation is slowing down. Working backwards, the Earth was rotating faster in the past, which means it had more rotational inertia to transfer to the moon, which infers the moon probably moved away from the Earth faster in the past, somewhat more than the current 3.8 cm/year.

So, when you take that into account, the math tends to work out better, such that you can add up over 4 billion years of recession to the original distance and come up with the current distance.

Cool another moon thread! The last one had some good info as does this one.

My only question is...Wouldn't a collision with a mars sized planet completely annihilate earth?

I've read meteors hit with force like 100 atomic bombs, and those aren't planet sized or even close to planet sized.

Shoot one more question just popped into my head...Was this planet just orbiting the sun on a collision course with earth?

As in where did this planet come from? How often do planets just slam into each other?

originally posted by: Arbitrageur

originally posted by: OccamsRazor04

Your figures are wrong.

402,336 km = Distance between the Moon and Earth

22,500 km = Original Distance

379,836 = 402,336 km - 22,500

3.78 cm = distance the Moon moves / year

3780000000 cm = Distance after 1 Billion years

378,000 km

You were right up until you converted cm to km, off by a factor of 10 there, should be 37,800km. While that's an accurate calculation, it's not the right number which I'll explain shortly.

originally posted by: OccamsRazor04

How is 22,000 KM touching?

Well if the moon is over 4 billion years old, then there's no way it could move 378,000 km per billion years for 4 billion years and be only 402,336 km away, so the math doesn't work. Even with the corrected conversion of 37,800 km, it doesn't add up to 402,336 km away after over 4 billion years.



So what's the solution?



As the moon is moving away, the Earth's rotation is slowing down. Working backwards, the Earth was rotating faster in the past, which means it had more rotational inertia to transfer to the moon, which infers the moon probably moved away from the Earth faster in the past, somewhat more than the current 3.8 cm/year.



So, when you take that into account, the math tends to work out better, such that you can add up over 4 billion years of recession to the original distance and come up with the current distance.

You are right. I just looked fast and didn't catch the error! Thanks.

My main point was that the person saying the Moon would be WAY too far out was wrong, which my error makes them even more wrong

I was actually surprised the numbers were so close because I figured distance would cause the distance/year to alter. Im at work though so didnt really look into it.

originally posted by: SuicideKing33
Cool another moon thread! The last one had some good info as does this one.



My only question is...Wouldn't a collision with a mars sized planet completely annihilate earth?



I've read meteors hit with force like 100 atomic bombs, and those aren't planet sized or even close to planet sized.



Shoot one more question just popped into my head...Was this planet just orbiting the sun on a collision course with earth?



As in where did this planet come from? How often do planets just slam into each other?

Yes, it would, and yes it did. (somewhat) The angle of the impact is important to note.

originally posted by: Bilk22
a reply to: IsaacKoi

What leads them to believe there was another planet roaming around and where did it get that name? Shouldn't we ask that first?

It was an hypothesis and now it gets more weight. It's quite an old hypothesis.

In 1898, George Darwin made the suggestion that the Earth and Moon had once been one body. Darwin's hypothesis was that a molten Moon had been spun from the Earth because of centrifugal forces, and this became the dominant academic explanation. Using Newtonian mechanics, he calculated that the Moon had orbited much more closely in the past and was drifting away from the Earth. This drifting was later confirmed by American and Soviet experiments, using laser ranging targets placed on the Moon.

Nonetheless, Darwin's calculations could not resolve the mechanics required to trace the Moon backward to the surface of the Earth. In 1946, Reginald Aldworth Daly of Harvard University challenged Darwin's explanation, adjusting it to postulate that the creation of the Moon was caused by an impact rather than centrifugal forces. Little attention was paid to Professor Daly's challenge until a conference on satellites in 1974, during which the idea was reintroduced and later published and discussed in Icarus in 1975 by Drs. William K. Hartmann and Donald R. Davis. Their models suggested that, at the end of the planet formation period, several satellite-sized bodies had formed that could collide with the planets or be captured. They proposed that one of these objects may have collided with the Earth, ejecting refractory, volatile-poor dust that could coalesce to form the Moon. This collision could potentially explain the unique geological and geochemical properties of the Moon.

A similar approach was taken by Canadian astronomer Alastair G. W. Cameron and American astronomer William R. Ward, who suggested that the Moon was formed by the tangential impact upon Earth of a body the size of Mars. It is hypothesized that most of the outer silicates of the colliding body would be vaporized, whereas a metallic core would not. Hence, most of the collisional material sent into orbit would consist of silicates, leaving the coalescing Moon deficient in iron. The more volatile materials that were emitted during the collision probably would escape the Solar System, whereas silicates would tend to coalesce.

And the name came from the Greek mythology like all planetary bodies of our system. Theia daughter of Gaia and Uranus.


Astronomy is a cool science, people should read books sometimes.

It Sounds like it came from Ur-anus BBC!

originally posted by: SpaceGoatFarts

originally posted by: Bilk22
a reply to: IsaacKoi

What leads them to believe there was another planet roaming around and where did it get that name? Shouldn't we ask that first?

It was an hypothesis and now it gets more weight. It's quite an old hypothesis.

In 1898, George Darwin made the suggestion that the Earth and Moon had once been one body. Darwin's hypothesis was that a molten Moon had been spun from the Earth because of centrifugal forces, and this became the dominant academic explanation. Using Newtonian mechanics, he calculated that the Moon had orbited much more closely in the past and was drifting away from the Earth. This drifting was later confirmed by American and Soviet experiments, using laser ranging targets placed on the Moon.

Nonetheless, Darwin's calculations could not resolve the mechanics required to trace the Moon backward to the surface of the Earth. In 1946, Reginald Aldworth Daly of Harvard University challenged Darwin's explanation, adjusting it to postulate that the creation of the Moon was caused by an impact rather than centrifugal forces. Little attention was paid to Professor Daly's challenge until a conference on satellites in 1974, during which the idea was reintroduced and later published and discussed in Icarus in 1975 by Drs. William K. Hartmann and Donald R. Davis. Their models suggested that, at the end of the planet formation period, several satellite-sized bodies had formed that could collide with the planets or be captured. They proposed that one of these objects may have collided with the Earth, ejecting refractory, volatile-poor dust that could coalesce to form the Moon. This collision could potentially explain the unique geological and geochemical properties of the Moon.

A similar approach was taken by Canadian astronomer Alastair G. W. Cameron and American astronomer William R. Ward, who suggested that the Moon was formed by the tangential impact upon Earth of a body the size of Mars. It is hypothesized that most of the outer silicates of the colliding body would be vaporized, whereas a metallic core would not. Hence, most of the collisional material sent into orbit would consist of silicates, leaving the coalescing Moon deficient in iron. The more volatile materials that were emitted during the collision probably would escape the Solar System, whereas silicates would tend to coalesce.

And the name came from the Greek mythology like all planetary bodies of our system. Theia daughter of Gaia and Uranus.


Astronomy is a cool science, people should read books sometimes.

Thanks for the response and yes, Astronomy is a cool science. I also am aware of where the names for the know planetary came from. The last part was unnecessary I have lots of other interests that consumes my reading time, but if you have one book in particular that you recommend, well I'll take a look. Got A's in my college astronomy classes, but that was quite a while ago

a reply to: IsaacKoi

It also raises the question of how it crashed so perfectly as to be just the right size and distance from the Earth for it all to "work".
Firepiston

So what is the theory? Was this a drive by hit? Does anyone believe that even a glancing collision between two planets would be less than catastrophic for both planets? Wheres the other planet? Are the earth and the chunk able to re-round themselves? None of the theory makes any sense.

Immanuel Velikovsky

a reply to: Bilk22

Sorry it wasn't necessary indeed (nor directed at you)

There is this massive book which is a superb introduction with gorgeous, huge pictures


www.amazon.com...=sr_1_1?s=books&ie=UTF8&qid=1402066621&sr=1-1&keywords=cosmos+sparrow

a reply to: tmeister182

Seriously people, you should just do some searches by yourself sometimes. It's not hard. Just Google Theia.

I posted the theory just above your post. Maybe you should look at it before asking the same questions?

It was (supposedly) a cataclysmic event, but it was also during a time the Earth was still forming and cooling. The other planetoid is now destroyed and absorbed. Yes planets in formation can reround themselves. An active planet is mainly molten, the crust is very thin. We are literally a small crust surfing on a ball of magma. That's why continents are drifting.

The theory makes perfect sense unless you don't understand what you are talking about.

originally posted by: agsz5
Immanuel Velikovsky

That was way before that. The moon is almost the same age as the earth.

Velikowsky's theory isn't about the formation of the moon at all. It's what was used by the "thunderbolts of the gods" people to theorize the planets were chaotic 10.000 years ago.

originally posted by: smurfy

originally posted by: IsaacKoi

"Moon created in violent collision with Earth, clues in Apollo rocks suggest"

That first part of The Guardian header looks a little misleading, until you sense it out!

It's early days yet though. They seem to be saying that there are similarities between the Moon and Earth, yet not the same, and again similarities between Earth and theoretical Theia, but not the same. So now they would need to go to the Moon and do a little mining...sorry digging, to get more pristine rocks.

The other thing is, where is the rest of the material from the original collision..there has to be some? Why should the Moon have formed out of all of it if Theia disintegrated, and why should Theia have disintegrated.

Given the theoretical size of Theia (size of Mars), the time taken for the collision to happen would have been several hours. Anyone on the surface of primordial Earth would have seen Theia getting larger and larger, up until the collision occurred. The energy released would have turned both planets back into molten rock. Depending on the velocity and collision angles, either the moon was formed from the debris thrown up from the initial collision or what was left of Theia, or perhaps a mix of the two. It could be that Theia is now part of the core of the Earth.

The best simulations look no different from the opening shot of a snooker contest.

originally posted by: stormcell
The energy released would have turned both planets back into molten rock.

Ermmm, Earth IS a molten rock

originally posted by: tmeister182
So what is the theory? Was this a drive by hit? Does anyone believe that even a glancing collision between two planets would be less than catastrophic for both planets? Wheres the other planet? Are the earth and the chunk able to re-round themselves? None of the theory makes any sense.

It's not a theory. It's a hypothesis, but if more evidence like this is confirmed it may become a theory.

Look at meteor crater in Arizona; the Earth fared much better then the object that hit the Earth. In the moon formation hypothesis, the Earth was also significantly larger and more massive than the object that struck it. Of course it was catastrophic, look at the impact simulation posted earlier in the thread, which also shows what happened to the other planet and where it is today, or at least the physics simulator's prediction of that.

It's impossible for bodies over a certain size to not re-round themselves to some extent, which is why all planets are essentially spherical, but asteroids can have irregular shapes, because they are below this rounding threshold caused by gravity. Of course the planets aren't perfect spheres; Mars in particular has a huge volcano and a huge canyon compared to Earth's corresponding features.

a reply to: Arbitrageur


Asteroids are irregular because they are cold.

Most planets are or were molten, that's why they are spherical, not just because of their size.

Also Mars is round, geological features are anecdotal compared to the scale of a planet, and volcanoes are caused by volcanism.

If the moon was once part of the earth, how come only the earth ended up with all the water, air, vegetation and life?

originally posted by: OccamsRazor04

originally posted by: Telos
I thought the moon once part of earth theory was just that, a theory and not scientifically proven.



Was the moon once part of Earth?



Did Venus Give Earth the Moon? Wild New Theory on Lunar History



etc... There are to many theories out there. Just pointing out that.

It's all but certain the Moon came from the Earth after another planet collided with the Earth. It's impossible to determine the evidence any other way.

I know that in threads like this one is very important to back up everything we say but (unfortunately I cannot recall where) I've read that moon's composite is different from earth's which makes a once part of earth argument not valid. Again, I cannot remember where I've read it but I can recall was an extensive study with a lot of scientific data.

And since I like the topic a lot I've tried to keep myself updated on the matter. So far I haven't read anything that makes it such a sure thnig or all but certain (as you state it).

originally posted by: SpaceGoatFarts
a reply to: Arbitrageur


Asteroids are irregular because they are cold.

Most planets are or were molten, that's why they are spherical, not just because of their size.

Also Mars is round, geological features are anecdotal compared to the scale of a planet, and volcanoes are caused by volcanism.

Ceres and some other asteroids are quite spherical, thank you.
It is not size that matters, it is mass. It is gravity which causes the spherical shape.
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