QuestionEarth Moon Origin

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Harry Costas

Like I said it will take me two years to make up my mind or have and idea of how the moon formed.

[Submitted on 8 Dec 2020 (v1), last revised 18 May 2021 (this version, v3)]

A Theory and Calculation of Lunar Center of Mass Shift and the Crustal Thickness Difference Between Far and Near Sides of the Moon​

Otto B. Bischof
The cause for the difference in crustal thickness between the far and near sides of the moon has been considered an open problem in astronomy since 1959 when the Soviet spacecraft Luna 3 sent back the first images of the lunar farside. The problem is referred to as the lunar farside highlands problem. In this article, the author deduces the center of mass shift of the moon from its geometrical center and the difference in crustal thickness between the far and near lunar sides necessary to explain it. Although there have been other theories proposed to explain these phenomena, this theory explains them as arising naturally from the effects on lunar material due to the earth's external gravity force and the moon's synchronous rotation and revolution. The author's mathematical model results in a calculated value of 1.6 km for the center of mass shift and a crustal thickness difference of 16 km. The author's deduced values of center of mass shift and crustal thickness difference are close to within about 5 to 10% of their accepted values. One unexpected and deducible result of the author's theory is that the center of mass shift of the moon is decreasing towards moon center under lunar recession at the current rate of about 1.6 x 10-4 mm/yr.

Harry Costas

It's going to take time to understand.

[Submitted on 10 Apr 2023]

Rapid solidification of Earth's magma ocean limits early lunar recession​

Jun Korenaga
The early evolution of the Earth-Moon system prescribes the tidal environment of the Hadean Earth and holds the key to the formation mechanism of the Moon and its thermal evolution. Estimating its early state by backtracking from the present, however, suffers from substantial uncertainties associated with ocean tides. Tidal evolution during the solidification of Earth's magma ocean, on the other hand, has the potential to provide robust constraints on the Earth-Moon system before the appearance of a water ocean. Here we show that energy dissipation in a solidifying magma ocean results in considerably more limited lunar recession than previously thought, and that the Moon was probably still at the distance of ∼7-9 Earth radii at the end of solidification. This limited early recession aggravates the often overlooked difficulty of modeling tidal dissipation in Earth's first billion years, but it also offers a new possibility of resolving the lunar inclination problem by allowing the operation of multiple excitation mechanisms.

Phillip Huggan

When the Moon forms within a million years later the energy is lost to electrostatic forces enough the dust is harmful today. One million yrs more energy (not there for our Moon) the sedimentation turns dust to asbestos. Only 500k yrs of energy is dust free.
If there is a Jetson's Earth-G world around Sirius its dust should be plowed 10m deep. If there is another bigger one with a Pb dusty Moon the PB is all the way through heavier than median weight composition.

Harry Costas

I added this paper even though I questions, that will come later

[Submitted on 29 May 2023]

The origin of the terrestrial planets​

Richard B. Firestone
Three major planets, Venus, Earth, and Mercury formed out of the solar nebula. A fourth planetesimal, Theia, also formed near Earth where it collided in a giant impact, rebounding as the planet Mars. During this impact Earth lost ≈4\% of its crust and mantle that is now is found on Mars and the Moon. At the antipode of the giant impact, ≈60\% of Earth's crust, atmosphere, and a large amount of mantle were ejected into space forming the Moon. The lost crust never reformed and became the Earth's ocean basins. The Theia impact site corresponds to Indian Ocean gravitational anomaly on Earth and the Hellas basin on Mars. The dynamics of the giant impact are consistent with the rotational rates and axial tilts of both Earth and Mars. The giant impact removed sufficient CO2 from Earth's atmosphere to avoid a runaway greenhouse effect, initiated plate tectonics, and gave life time to form near geothermal vents at the continental margins. Mercury formed near Venus where on a close approach it was slingshot into the Sun's convective zone losing 94\% of its mass, much of which remains there today. Black carbon, from CO2 decomposed by the intense heat, is still found on the surface of Mercury. Arriving at 616 km/s, Mercury dramatically altered the Sun's rotational energy, explaining both its anomalously slow rotation rate and axial tilt. These results are quantitatively supported by mass balances, the current locations of the terrestrial planets, and the orientations of their major orbital axes.

rod

rod

FYI, there are many giant impact models out now for the origin of the Moon and how Earth-Moon orbit the Sun, just right as a pair. Chaning various model inputs, can result in some very different, and dramatic differences too for the final outcome.

Giant impact could have formed the Moon more rapidly, scientists reveal in new simulations, https://phys.org/news/2022-10-giant-impact-moon-rapidly-scientists.html

"Scientists from Durham University's Institute for Computational Cosmology used the most detailed supercomputer simulations yet to reveal an alternative explanation for the Moon's origin, with a giant impact immediately placing a Moon-like body into orbit around Earth. The researchers simulated hundreds of different impacts, varying the angle and speed of the collision as well as the masses and spins of the two colliding bodies in their search for scenarios that could explain the present-day Earth-Moon system."

Moon's crust may have formed from 'slushy' magma ocean long ago, https://www.space.com/moon-crust-formation-slushy-magma-ocean

“The moon's crust might have formed from an unevenly layered "slush" of magma that once covered the entire body, a new study reports. It's the latest turn of the wheel on scientists' picture of how the moon and its features formed, a picture that's been continually changing ever since Apollo astronauts brought moon rocks back to Earth in the late 1960s and early 1970s."

TWO IMPACTS, NOT JUST ONE, MAY HAVE FORMED THE MOON, https://skyandtelescope.org/astronomy-news/two-impacts-not-just-one-may-have-formed-the-moon/

"Moon formed with a bang, when a protoplanet the size of Mars hit the newborn Earth. Evidence from Moon rocks and simulations back up this idea. But a new study suggests that the protoplanet most likely hit Earth twice. The first time, the impactor (dubbed "Theia") only glanced off Earth. Then, some hundreds of thousands of years later, it came back to deliver the final blow. The study, which simulated the literally Earth-shattering impact thousands of times, found that such a “hit-and-run return” scenario could help answer two longstanding questions surrounding the creation of the Moon."

Question: How many different giant impact simulations are now documented, and how many different outcomes are documented now? Who, what, when, where, how, and why investigative reporting on this topic is greatly needed IMO.

rod

Another question, how many exoplanets are confirmed now? 5502 at this site, http://exoplanet.eu/

5496 confirmed at this site, https://exoplanetarchive.ipac.caltech.edu/index.html

I have not read a report yet where astronomers observed an exomoon form around any of these and could see the *giant impact* create the moon IMO, the giant impact scenario exists in computer simulations. Eventually, real world or natural world observations must be documented too here.

Harry Costas

Hello Rod

Thank you for the information.

The problem I have with impact models is this.
How did the Moon and Earth result in uniform motion.

When the Solar System was formed.
Every planet had much more moons, via Chaos model.
The moons that did not have Uniform motion collided with each planet, explaining large impacts and sharing matter.
The Earth has had Crustal plate movement and recycling of the crust.
The moon may have had limited movement of the crust.
I have to give this more thinking.

The Moon does not spin.
The face facing earth will have different flat features compared to the Dark Side, mountains.

Harry Costas

Hopefully in the near future we will have more information of the moon to work out the origin.
[Submitted on 21 Aug 2023]

Chandrayaan-3 Alternate Landing Site: Pre-Landing Characterisation​

K. Durga Prasad, Dibyendu Misra, Amitabh, Megha Bhatt, G. Ambily, Sachana Sathyan, Neeraj Srivastava, Anil Bhardwaj
India's third Moon mission Chandrayaan 3 will deploy a lander and a rover at a high latitude location of the Moon enabling us to carry out first ever in-situ science investigations of such a pristine location that will potentially improve our understanding on primary crust formation and subsequent modification processes. The primary landing site (PLS), is situated at 69.367621 degS, 32.348126 degE. As a contingency, an alternate landing site (ALS) was also selected at nearly the same latitude but nearly 450 km west to PLS. In this work, a detailed study of the geomorphology, composition, and temperature characteristics of ALS has been carried out using the best-ever high resolution Chandrayaan 2 OHRC DEMs and Ortho images, datasets obtained from Chandrayaan 1 and on-going Lunar Reconnaissance Orbiter. For understanding the thermophysical behaviour, we used a well-established thermophysical model. We found that the Chandrayaan 3 ALS is characterised by a smooth topography with an elevated central part. The ALS is a scientifically interesting site with a high possibility of sampling ejecta materials from Tycho and Moretus. Based on the spectral and elemental analysis of the site, Fe is found to be near approx. 4.8 wt.%, with Mg approx. 5 wt.%, and Ca approx. 11 wt.%. Compositionally, ALS is similar to PLS with a highland soil composition. Spatial and diurnal variability of around 40 K and 175 K has been observed in the surface temperatures at ALS. Although belonging to similar location like PLS, ALS showed reduced daytime temperatures and enhanced night-time temperatures compared to PLS, indicating a terrain of distinctive thermophysical characteristics. Like PLS, ALS is also seems to be an interesting site for science investigations and Chandrayaan 3 is expected to provide new insights into the understanding of lunar science even if it happens to land in the alternate landing site.

rod

Hello Rod

Thank you for the information.

The problem I have with impact models is this.
How did the Moon and Earth result in uniform motion.

When the Solar System was formed.
Every planet had much more moons, via Chaos model.
The moons that did not have Uniform motion collided with each planet, explaining large impacts and sharing matter.
The Earth has had Crustal plate movement and recycling of the crust.
The moon may have had limited movement of the crust.
I have to give this more thinking.

The Moon does not spin.
The face facing earth will have different flat features compared to the Dark Side, mountains.
Harry Costas, you stated: "The Moon does not spin."

The Moon does have a very slow spin on its axis as the Moon orbits Earth. Each month, Sky & Telescope magazine publishes the various carters that become visible on the *far side*, lunar librations. You need good telescopes with higher magnification to see some of these lunar librations where part of the far side or *dark side* becomes visible from Earth. About 59% of the Moons surface is viewable from Earth but the Moon does slowly spin as it moves around the Earth.

skynr13

Harry Costas, you stated: "The Moon does not spin."

The Moon does have a very slow spin on its axis as the Moon orbits Earth. Each month, Sky & Telescope magazine publishes the various carters that become visible on the *far side*, lunar librations. You need good telescopes with higher magnification to see some of these lunar librations where part of the far side or *dark side* becomes visible from Earth. About 59% of the Moons surface is viewable from Earth but the Moon does slowly spin as it moves around the Earth.

But the Moon never does spin completely around because it is tidally locked in position. It only wobbles a bit and when it does, some of the darkside shows for a time.

rod

But the Moon never does spin completely around because it is tidally locked in position. It only wobbles a bit and when it does, some of the darkside shows for a time.
Other sources on this subject read differently here.

From my 1963 How And Why Wonder Book of The Moon, page 19, Why do we see only one side of the moon?

"The moon rotates on its axis and in the same direction to produce night and day on the moon. But there is one great difference. The moon rotates on its axis only once every 27 1/3 days, or, once during each time it orbits the earth."

The information explains why the moon rotates completely and we see only one side as the moon orbits earth. NASA has this info on the topic.

The giant impact model is discussed with a much faster spinning moon initially and much closer to earth also. Details of how this all worked out to the Moon we see today remains very challenging. I know using my telescopes I do not see a Moon some 3-6 earth radii away with an angular size some 10x larger or more in the night sky

billslugg

10X ar larger angular diameter of the Moon occurs only when it hits your eye ike a big pizza pie, which is very rare.

From the reference frame of a person standing on the Earth, the Moon rotates once every day minus about an hour. It is going around us once a day (minus 50 min) always showing the same side. 365 plus 13 times per year or 378 times per year.

From the reference frame of a person floating in space above the North Pole, the Moon rotates once per 28 days, 13 times a year..

From the reference point of a person floating above the Sun's north pole, the Moon spins 14 times per year..

Helio and Atlan0001

rod

10X ar larger angular diameter of the Moon occurs only when it hits your eye ike a big pizza pie, which is very rare.

From the reference frame of a person standing on the Earth, the Moon rotates once every day minus about an hour. It is going around us once a day (minus 50 min) always showing the same side. 365 plus 13 times per year or 378 times per year.

From the reference frame of a person floating in space above the North Pole, the Moon rotates once per 28 days, 13 times a year..

From the reference point of a person floating above the Sun's north pole, the Moon spins 14 times per year..
"10X ar larger angular diameter of the Moon occurs only when it hits your eye ike a big pizza pie, which is very rare."

billslugg, indeed this appearance of the Moon in the night sky would be *very rare*. That would be about its diameter if the Moon was about 6 earth radii distance compared to its present mean near 60.3 earth radii. We get lunar sizes like that in the sky using the giant impact model for the origin of the Moon, when the debris disc accretes to form the Moon some 3-6 earth radii away initially and then expands outward to its current location and orbit. The Moon when it first formed in the giant impact model would be some 5.18 degrees across or perhaps larger if closer to the early earth in the model (3 earth radii for example) with an orbital period around earth < 21 hours for the lunar month. When it comes to my telescope observations of the Moon, I do not see anything like that when viewing Such views apparently exist only in computer simulations.

Helio

billslugg

Once the oceans formed, can you imagine the height of the tides when the Moon was at such close distances?

My Celestron 25x100's give me an apparent diameter about 12°. It's a bit too bright, I have no ND filters other than solar. For the Moon I may go pick up a couple sheets of #5 welding glass.

Full Moon at 25x always best low on the horizon. Very cool.

Pogo

Bill, haven’t tried it with my 10” Meade, but, I’ve read you could cut two 2” or 3” circular holes opposite center on a piece of cardboard and tape it in front of the objective. Same aperture, less light.

Maybe two such cardboards, mount them together, end slightly rotating one varies the opening, hence the brightness.

Helio

Bill, haven’t tried it with my 10” Meade, but, I’ve read you could cut two 2” or 3” circular holes opposite center on a piece of cardboard and tape it in front of the objective. Same aperture, less light.

Maybe two such cardboards, mount them together, end slightly rotating one varies the opening, hence the brightness.
The reduction would be the square of the dia. ratio. So a 2” dia. hole would cut it to 1/25th the brightness. This would be about 1/2 the brightness of a quarter Moon since a full Moon is 12x brighter than a quarter Moon.

But, there may be additional reduction if the exit pupil of the scope is such that the additional magnification due to the increase in the focal ratio causes some of the light to not enter the pupil.

I usually ignore full Moons since surface features are far better to see with shadows.

billslugg

I like the cardboard idea. I have no need for such a large aperture with such a bright object and such a low power.

Pogo

I think most observers ignore the moon near full, no shadows most features washed out. Near the quarter moon gets you shadows and better features.

Helio and billslugg

Helio

I think most observers ignore the moon near full, no shadows most features washed out. Near the quarter moon gets you shadows and better features.
Yep. There is a day about the time of the waxing quarter that reveals an “X” pattern, due to mountain ridges.

X pattern
After months of set-up, I enjoyed “first light” on my new scope in seeing great lunar features of the 1/4 Moon, including the rebounded central crater peaks.

billslugg

Harry Costas

Imagine that.
We see the one face of the moon and yet it rotates.
It must be a magic trick.
Face on Face off

Pogo

From Earth’s viewpoint, it does not ‘seem to rotate’, but, from the Moon’s viewpoint, it rotates once per orbital revolution, the Sun rises, the Sun sets. One day equals one month.

Harry Costas

Maybe we should look at the origin of our Milky Way to find the answers to the origin of our moon and our planets.

[Submitted on 29 Jun 2023]

The History of The Milky Way: The Evolution of Star Formation, Cosmic Rays, Metallicity, and Stellar Dynamics over Cosmic Time​

Jiro Shimoda, Shu-ichiro Inutsuka, Masahiro Nagashima
We study the long-term evolution of the Milky Way (MW) over cosmic time by modeling the star formation, cosmic rays, metallicity, stellar dynamics, outflows and inflows of the galactic system to obtain various insights into the galactic evolution. The mass accretion is modeled by the results of cosmological N-body simulations for the cold dark matter. We find that the star formation rate is about half the mass accretion rate of the disk, given the consistency between observed Galactic Diffuse X-ray Emissions (GDXEs) and possible conditions driving the Galactic wind. Our model simultaneously reproduces the quantities of star formation rate, cosmic rays, metals, and the rotation curve of the current MW. The most important predictions of the model are that there is an unidentified accretion flow with a possible number density of ∼10−2 cm−3 and the part of the GDXEs originates from a hot, diffuse plasma which is formed by consuming about 10 % of supernova explosion energy. The latter is the science case for future X-ray missions; XRISM, Athena, and so on. We also discuss further implications of our results for the planet formation and observations of externalgalaxies in terms of the multimessenger astronomy.

Harry Costas

The impact theory leads to a chaos motion.
A uniform motion from the chaos, during the formation of our solar system, all planets and their moons would have collided and out of the picture.
Well that my opinion.

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