The Moon: What is it's purpose?

First a comment on the Roche limit. This is the distance at which a body lacking internal cohesiveness or strength would disrupt. That would work on rubble asteroids, but the distance would have to be less to disrupt a cohesive body. I have no idea how much of difference this would make, but recall reading that it is significant (though not by an order of magnitude).

Whoa! 17% of the surface is covered by Mare basalts.

In addition "Mare basalts may be more extensive than their surface exposure indicates and extend under some of the highland light plains units, covered by debris from basin-forming collisions". (Taylor, S.R. Planetary Science: A Lunar Perspective Lunar and Planetary Institute, p265)

Further, "Although evidence for volcanism prior to +/- 4.0 b.y. remains speculative, there is reason to believe that volcanic processes were operative during the extensive fractionation of the lunar crust." (Basaltic Volcanism on the Terrestrial Planets Lunar and Planetary Insitute p279)

The moon is the product of extensive volcanism modified by impacts, ranging from the massive planetesimals that carved out the huge impact basins, down to the micro-meteoroid impacts that have generated the lunar regolith.

I agree with all your other points, that one just seemed injudicious.

 

Log in or Sign up to hide all adverts.

Log in or Sign up to hide all adverts.

I remember reading something similar, yet the wikipedia file seems to indicate other than how I read it. It gives the moons ideal break up range above the Earth's surface and it is fairly cohesive.

Come on, Trippy, you're talking about rock surrounded by kilometers of ice. Of course Hydrostatic equalibrium is playing a part in materials maleable to liquidizing. That could have happened at any time. (in stellar terms) and through bombardment.

The moon isn't made of ice. It's rock, 3.6 Billion years old volcanic, rapidly cooled. Hydrostaic equalibrium? I'm not sure about that. Seems more like centrifugal force.

You'll have to explain furuther against coformation for me to comment further. But it seems like you're using current day figures in a very uniform fashion. Now doesn't mean always was or has been.

 

Log in or Sign up to hide all adverts.

No doubt essentially true, but not firm proof of volcanic activity. I said I tended to agree that the moon was not significantly volcanic. There are several reasons why I think this probably true. The two most important are:

(1) With much higher surface to volume ratio and much smaller heat transport distance to the surface which has no IR reflecting atmosphere above, the moon would lose heat that was produced internally by radioactive decay much more rapidly than the Earth does. I almost never search but suspect that there is no molten core inside the moon. It may have been one relatively briefly once as gravitation infall energy was converted to heat, especially if the infalling matter was already hot because it came from an Earth impact ejection of it.

(2) Most significant radioactive materials (K40 a slight exception) tend to be very dense so are found mainly in the interior of the Earth (or matter which was once there) - not much would have been ejected by the impact that made the moon from mantel crust.

SUMMARY of (1) & (2): I doubt that the heat production rate from radioactivity inside the moon can sustain a temperature at which rocks are molten against the radiative heat loss from the surface (dark side only) If that is the case then there is no volcanic activity as I would define "volcanic activity"

I explain the 17% of basalt sea by stealing from your text, slightly modified as:

"the product of extensive ... impacts, ranging from the massive planetesimals that carved out the huge impact basins, down to the micro-meteoroid impacts that have generated the lunar regolith. " I.e. there is no doubt that many impacts dissipate rapidly more than enough energy to liquefy their own mass and good bit of the moon mass impacted. This liquid material would rapidly take an equipotentail (near spherical surface).

It might be interesting to very carefully determine the radius of curvature of some of the older nearly equatorial mares. Now the moon takes ~28 days to make one 360 rotation but earlier, when it was closer to Earth its spin rate was higher. Thus the moon was less spherical - a larger equatorial circumference / larger radius of curvature for the equipotential surface and also flatter pole regions. Perhaps the oldest mares still have slightly flatter surfaces than the current equipotential surface? As they would not be far from hydrostatic equilibrium even today (small stresses) they may be "stiff enough" remember at least part of their first rigid shape. This idea could probably be tested form Earth, either by highly accurate laser range measurements. Radar might also work, but as it would hit the entire sea area there would be some complex (perhaps impossible) mathematical processing of the return signal pulses. Their single pulse strength as function of time to pull the radius of curvature out of the signals.

Again, if there is any good reason / facts to think that the seas were volcanic in origin, I will yield to it as I am just speculating.

 

I accept the standard answer. A fractured planet. The iron meteors are from the core of it and the stony ones (all with the same age) are form the surface of it.

What fractured it is the interesting question. In one wild post I once suggested in jest their Dr. Stangelove set off a super hydrogen bomb deep in the interior.

Earth ran a natural, water moderated, fission reactor in Africa for several thousand years. It shut down periodically when it boiled the water away and then started up again when the rains has re-saturated the uranium ore. -We know all this as the uranium ore there is already depleted in U235 and the fission product agree. (I forget the details, but because the radioactive fission products decay at different rates and can some can be stablized by neutron capture, we even know the cycle times rather well.) I would not be too surprized to find that at the asteroid orbits the heavy (read radioactive) elements were starting to condense out of the solar system cloud rapidly. More distant from the sun planets are more gas like. Perhaps that Planet was doomed from the start by too much internal radioactivity. Again just my speculations. - I like to speculate, using the physics I know, instead of search for facts which can be boring and seldom lead to more interesting thoughts.
---------
*If it exploded by run-away-nuclear fission, the natural reactor would need to have had a positive thermal coefficient of reactivity - like Chernobal had.

 

That is an incredibly out-of-date answer, Billy. In all currently accepted hypotheses, Jupiter (and Saturn to a lesser extent) put the kibosh on planetary formation. There is no need to invoke a fractured planet.; there was no planet to fracture.

Some reading:

Kortenkamp, S.J., Wetherill, G.W., "Formation of the Asteroid Belt", 31st Annual Lunar and Planetary Science Conference (2000).
http://adsabs.harvard.edu/abs/2000LPI....31.1813K

Scott, E.R.D., "Meteoritical and dynamical constraints on the growth mechanisms and formation times of asteroids and Jupiter", Icarus, 185:1, 72-72 (2006).
http://arxiv.org/abs/astro-ph/0607317

Djakov, B.B., Reznikov, B.I., "Computer simulation of the formation of asteroid belt structure", Moon and the Planets, 25, 113-128 (1981).
http://adsabs.harvard.edu/abs/1981M&P....25..113D

 

Thanks- I am an incredibly old guy, whose memory still works. I will get to your links as soon as I can, but it may be a day or so. Again thanks for the up-date.
Until I do, I am wondering how the nearly pure iron nickel meteors formed, if not in the core of a fractured planet? Any quick comments on that? (It does not seen possible, to me that they just condensed that pure from a cloud. If they did, they would be vapor deposited big crystal, not melted masses, at least in the cores of the bigger ones that did not melt on the way down thru the atmosphere also seems to be a problem.)

 

Are telling me there are natural reactors in planetary bodies?
I thought these elements were denser than the surrounding rock. I'm guessing currents bring it up from the core because I would have suppected that while the planet was motlen these elements would have settled in the center.

So it's possible this planet could have reached critical mass?
What do we know about the composition of the asteroid field?
I read up on Ceres 1 a few pages back, it composes 32 percent of the fields total volume. That means the there are a lot of small asteroids. circling the sun. Is this why you theorized the bomb? I'm not sure how seriously I should take the planetary bomb...it would take alot of Uraninium to blow up even a small planet.

 

Billy was talking about Oklo. References: http://www.ocrwm.doe.gov/factsheets/doeymp0010.shtml, http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor.

Anyhow, the exploded / fractured planet hypothesis has long fallen out of favor. Where are the remnants of the planet? The total mass of the asteroid belt is estimated to be about 0.1% of the Earth's mass. Some extra mechanism is needed to explain the paucity of mass. The explanation is Jupiter: It flung most of the asteroid belt mass out of the solar system. However, Jupiter adds another twist. A planet could not have formed. Obviously, planetesimals (bodies hundred meters to tens of kilometers in diameter) and protoplanets (tens of kilometers to 1000 km or so in diameter) did form (evidence: Ceres). Protoplanets could not combine to form a planet because of Jupiter's influence.

 

Thanks for the link to the natural fission reactor in Africa. I did not give any as just dredging things up from my memory is much easier than searching, for me.

You answered your question ("Where are the remnants of the planet?") and I might add that many small asteroids were all in nearly the same orbit (would be if from a fractured Planet) surely they would also do a lot of mutual scattering. which could give them more elliptical orbits. Then in next million years or so years they could again scatter off Mars (or even Earth) into the sun or into Jupiter etc. But with only 0.1% of Earth mass there now this mutual scattering soon lost any significance to Jupiter’s effects.

Jupiter is big (~1% of solar mass as I recall). Perhaps it was originally a gas ring around the sun. I.e. well collected in the radial direction into a relatively narrow band long before it collected together in azimuth angle. If this is feasible (and it seems at least possible to me) then the "Jupiter won't allow planet to form in the asteroid belt" argument, which currently makes the "fracture planet" out of favor as the origin of the asteroids, falls apart I think.

I would not object to a couple of "pre-asteroids" planets (say moon size or a little bigger) forming and melting their cores to make iron/nickel masses and then later mutually colliding to fracture.

I did skim two of the three links (one said abstract not available) and they seem to have swept my question "How did the iron/nickel asteroid/ meteors form, if not in at least moon like planet(s) cores?" under the rug.

We old timers get set in our ways (and beliefs) and do not give them up without a fight. (I am still addicted to my "relativistic mass" for example, but admit that the more modern POV is better.)

SUMMARY (two questions): How do you know that the tiny denser planet(s?) that fractured to make the asteroids did not form well before the large gas cloud mass could condense to make the planet called Jupiter? Where did the iron/nickel masses come from?

 

Yet Ceres isn't a planet.
Luna is large for a moon. I believe it fits the definition (new) for a planet.
But I didn't know H.E. was part of the definition.

I did, and do know this.
My point was how can we know the interior of the planetoid? It's covered in Ice and it's very flexible over a short amount of time to redistribution. Sources say it has a rocky core surrounded by a substantial amount of Ice...aparently it's out side the solar system's snow line. My question is "how can we assume this planetoid has suffiicent mass for H.E. and that it's shape is due to the mass rather than just the ice layering.

I fully realize this might be a stupid question but I simply don't know.

No it's not my assertion.
It's stating the obvious.

Wait, wait, wait.
Do you believe these are remenants of planets? Ceres, Vesta, etc.

Hmmm.
I didn't know this was a pseudo force. Fascinatinng.
I had assumed the motion of rotation on a plastic, nearly liquid body would have some effect on it's mass. I'm thinking about molten glass being spun on a pole. The spining pushes the greatest part of mass out away from the center.

I'm just saying I think the Moon started in a higher orbit.

Axis Tilts
Mercury 0
Venus 2.6
Earth 23.5
Mars. 25.2
Jupiter 3.08
Saturn 26.7
Uranus 97.9
Neptune 28.8
Pluto 98.8

Now it could be that the creation of the Solar System allowed the Distant Outter planets more freedom of axis. Theoreticaly the Sun would draw more "attention" of celestrial strike in the early periods. With a large amount of material still in the elliptical, bombardments upon the inner planets may likely could have been mostly along the equator. The Yucatan strike is in such a location and it appears to be of suffient size to have effected the Earth's axis (I'm making assumption) Of course the location of strike isn't as nearly important as how it opposes the planets center of gravity.

It just disturbs me, the jump from 2.0 to 23. degrees at Earth.
And then when I compare the perturbations to physical evidence of impacts, I see Earth and Moon system have significant impacts. Mars, at 25 degrees with significant surface deformation.

I think the Outter Planets are out of the equation because of the slackened grip of the Sun at these very very extreme distances. Yet and still Jupiter seems close enough to still be held some what tightly. Neptune seems remarkably well-behaved at 28 degrees.

It just seems there is reason to believe the Earth-moon system at some point after it's creation causing the shift drawing the moon closer, tilting the Earth's axis and causing a change in the moon's oribt around the Earth. Yes the probability of this happening is much greater in the Early solar system than down the line.

 

Also you seem not to know that part of the new definition is that a Planet must clear other objects (except its moons) from its orbit. The Moon is a moon because it has not done this. (And certainly the Earth is not a moon of the Moon.)

 

No there is no "pushing" away. The glass mass should leave the pole and follow a straight tangential line, but the pulling of the pole prevents almost all of this, unless the glass mass does separate from the pole.

 

Very well Trippy, I will differ to you as my knowledge is incomplete.

 

Doesn't temperature have a factor i Hydrostatic Equalibrium?
Ambient temperatures had to have been between 55 to 70 Kelvin in the begining and rose as the proto sun gained mass. Metals should have been granuals. That would explain the Hydrostatic Equalibrium of Ceres and Vesta...those forms were...I think made in the begining and are left overs.

You compared the Moon to those early formation planetoids that were in a very warm tempature enivorment. I'm not sure what the moon creation by colision theory says but I know ambient space is around 3 Kelvin. Cooling would happen much more rapidly.

I think I know what you're going to say though. You've said it already. Hydrostatic equilibrium classifies gravitation reorganization as well. It just irks me that such a colision would create the very smooth,very well distributed and well formed shape of Luna as it is to day with no irregularities from core to surface as some moons have.

It reminds me of the seperation of elements by gravity, heavier elements on the bottom...especially the amount particulate dust which makes up the moons surface., I don't know. I'll continue reading.