Question Earth Moon Origin

[Harry Costas]

Could this spin offer a solution to moon forming?

[Submitted on 30 May 2025]

Three fast-spinning medium-sized Hilda asteroids uncovered by TESS​

Nóra Takács, Csaba Kiss, Róbert Szakáts, Emese Plachy, Csilla E. Kalup, Gyula M. Szabó, László Molnár, Krisztián Sárneczky, Róbert Szabó, Attila Bódi, András Pál

Three fast-spinning medium-sized Hilda asteroids uncovered by TESS

Hilda asteroids, which orbit in a 3:2 resonance with Jupiter, serve as key indicators of dynamical processes in the early solar system. Their spin rates, an important probe of these mechanisms, can constrain their density and collisional evolution, offering valuable insights into their origin...

arxiv.org

 

[Harry Costas]

The search to be never ending in finding the origin of the moons.

[Submitted on 3 Jun 2025]

Clues for Solar System Formation from Meteorites and their Parent Bodies​

Bernard Marty, Katherine R. Bermingham, Larry R. Nittler, Sean N. Raymond

Understanding the origin of comets requires knowledge of how the Solar System formed from a cloud of dust and gas 4.567 Gyr ago. Here, a review is presented of how the remnants of this formation process, meteorites and to a lesser extent comets, shed light on Solar System evolution. The planets formed by a process of collisional agglomeration during the first hundred million years of Solar System history. The vast majority of the original population of planetary building blocks (~100 km-scale planetesimals) was either incorporated into the planets or removed from the system, via dynamical ejection or through a collision with the Sun. Only a small fraction of the original rocky planetesimals survive to this day in the form of asteroids (which represent a total of ~0.05% of Earth's mass) and comets. Meteorites are fragments of asteroids that have fallen to Earth, thereby providing scientists with samples of Solar System-scale processes for laboratory-based analysis. Meteorite datasets complement cometary datasets, which are predominantly obtained via remote observation as there are few cometary samples currently available for laboratory-based measurements. This chapter discusses how analysis of the mineralogical, elemental, and isotopic characteristics of meteorites provides insight into (i) the origin of matter that formed planets, (ii) the pressure, temperature, and chemical conditions that prevailed during planet formation, and (iii) a precise chronological framework of planetary accretion. Also examined is the use of stable isotope variations and nucleosynthetic isotope anomalies as constraints on the dynamics of the disk and planet formation, and how these data are integrated into new models of Solar System formation. It concludes with a discussion of Earth's accretion and its source of volatile elements, including water and organic species.

 

[Harry Costas]

This may not apply to the Earth and Moon.
It's worth noting the paper.

[Submitted on 4 Jun 2025]

Centaur Nuclei: Sizes, Shapes, Spins, and Structure​

Y. R. Fernandez, M. W. Buie, P. Lacerda, R. Marschall

We present a wide-ranging but in-depth analysis of Centaurs, focusing on their physical and structural aspects. Centaurs, originating from the Scattered Disk and Kuiper Belt, play a crucial role in our understanding of Solar System evolution. We first examine how biases in discovery and measurement affect our understanding of the Centaur size distribution. In particular we address the strong dependence of the census on perihelion distance and the broad distribution of Centaur geometric albedos. We explore the rotational characteristics derived from lightcurves, revealing a diverse range of spin rates and photometric variabilities, with most Centaurs showing low amplitude lightcurves, suggesting near-spherical shapes. Additionally, we investigate the relationships between Centaur orbital parameters, surface colors, and physical properties, noting a lack of correlation between rotational dynamics and orbital evolution. We also address the influence of sublimation-driven activity on Centaur spin states, and the rarity of contact binaries. We then discuss some observational and modeling limitations from using common observations (e.g. visible or infrared photometry) to determine diameters and shapes. Following that, we give some points on understanding how Centaur diameters and shapes can reveal the `primitive' nature of the bodies, emphasizing the important role occultation observations play. We also then assess how the Centaur size distribution we see today has been influenced by the collisions in both the primordial Kuiper Belt and in the subsequent Scattered Disk. Finally, we end the chapter with a short narrative of future prospects for overcoming our current limitations in understanding Centaur origins and evolution.

 

[Harry Costas]

Russia and China will set up a power station on the moon.
Hopefully, more info about the moon may lead to knowing its origin.

Google Search

 

[Harry Costas]

Impacts have had influences for over 5 billion years.
Imagine the mass accumulated.

[Submitted on 10 Jun 2025 (v1), last revised 11 Jun 2025 (this version, v2)]

Impact chronology of leftover planetesimals​

R. Brasser

After the formation of the Moon the terrestrial planets were pummelled by impacts from planetesimals left over from terrestrial planet formation. This work attempts to reproduce the impact rates set by modern crater chronologies using leftover planetesimals from three different dynamical models of terrestrial planet formation. I ran dynamical simulations for 1 billion years using leftover planetesimals from the Grand Tack, Depleted Disc and Implantation models of terrestrial planet formation with the GENGA N-body integrator. I fit the cumulative impacts on the Earth and Mars using a function that is a sum of exponentials with different weighing factors and e-folding times. Most fits require three or four terms. The fitted timescales cluster around t1=10 Myr, t2=35 Myr, t3=100 Myr and t4>200 Myr. I attribute them to dynamical losses of planetesimals through different mechanisms: high-eccentricity Earth crossers and the nu6 secular resonance, Earth crossers, Mars crossers, and objects leaking on to Mars crossing orbits from beyond Mars. I place a constraint on the initial population using the known Archean terrestrial spherule beds, and I conclude that the Archean impacts were mostly created by leftover planetesimals. The inferred mass in leftover planetesimals at the time of the Moon's formation was about 0.015 Earth masses. The third time constant is comparable to that of modern crater chronologies. As such, the crater chronologies are indicative of impacts by an ancient population of Mars crossers. The initial perihelion distribution of the leftovers is a major factor in setting the rate of decline: to reproduce the current crater chronologies the number of Earth crossers at the time of the Moon's formation had to be at most half of the Mars crossers. These results together place constraints on dynamical models of terrestrial planet formation.