scholarly journals Convection in the Moon

1972 ◽  
Vol 47 ◽  
pp. 377-383
Author(s):  
S. K. Runcorn
Keyword(s):  
Heat Transfer ◽  
Solid State ◽  
Remanent Magnetization ◽  
Second Harmonic ◽  
Crystalline Rocks ◽  
Hydrostatic Equilibrium ◽  
Iron Core ◽  
The Moon ◽  
History Of ◽  
The Moment

It is natural to inquire whether thermal convection is occurring in the Moon through solid state creep processes. The primary evidence is the departure of the Moon from the figure of hydrostatic equilibrium, but certain difficulties in the thermal history of the Moon are eased by assuming heat transfer by convection. If convection exists in the Moon it must have a second harmonic pattern, otherwise the lunar moments of inertia would not differ.Two important predictions of the marginal theory of convection: the existence of a core of radius 0.06–0.3 of the lunar radius (for a second ergee harmonic) and the value of 0.4 for the ratio of the dynamical to surface ellipticities now have support, the latter from the data of the heights of the lunar surface. The former prediction is compatible with the value of the moment of inertia factor now found if the Moon's interior is ‘hot’.Further the existence of a fluid iron core 3400 m.y. ago seems required as a result of the remanent magnetization of the crystalline rocks of the maria basins inferred from the remanent magnetization of the returned Apollo samples and the fields measured by the Apollo 12 and Explorer magnetomers.

Interpretation of lunar potential fields

1977 ◽  
Vol 285 (1327) ◽  
pp. 507-516 ◽  
Keyword(s):  
Magnetic Field ◽  
Gravity Field ◽  
Thermal Convection ◽  
Thermal History ◽  
Second Harmonic ◽  
Iron Core ◽  
The Moon ◽  
Laser Altimeter ◽  
Deep Interior ◽  
History Of

Understanding of the internal dynamics of the Moon must start from the interpretation of the gravitational and magnetic fields, both present and past. It has been long known from the study of Cassini’s laws and its librations that the Moon substantially departs from hydrostatic equilibrium. This is confirmed by the second harmonic of the gravitational field determined by the tracking of orbiting satellites which also reveals anomalies (the mascons) clearly associated with the processes by which the circular mare formed. The mascons must be retained by the finite strength of the lithosphere, although there is evidence that they may have subsided by about 1 km by slippage along cylindrical fault systems around these mare, and these processes may be important in discussing moonquakes and the lunar transient phenomena. The analyses of the present figure of the Moon by the geometrical librations and by the lunar laser altimeter of Apollo 15 and 16 and other space determinations now seem essentially in agreement. The data gives evidence of the figure of the Moon prior to the filling of the mare, i.e. before about 3300 Ma and it can be concluded that the present non-hydrostatic low harmonics of the gravity field were not then present. Comparison between the present figure of the Moon and its gravity field show that there is a low harmonic variation in density in the deep interior. Both these conclusions point to thermal convection described by second degree harmonics as being the cause of the present non-hydrostatic shape of the Moon. The present lunar dipole magnetic field has been shown by successive analyses to be negligible, the most recent value being 0.05 nT at the surface. Yet magnetic anomalies near the surface of the Moon have been discovered: 1 nT at heights of 100 km and 10-30 nT with length scales of 10 km at the surface. These anomalies must arise from the magnetization of the crustal rocks as discovered in the returned samples. These various data conclusively show that the Moon between 4000 and 3200 Ma possessed a field of internal origin, probably dipolar, with an intensity which seemed to have diminished from over 1 Gat 4000 Ma to a few thousand nT at 3.200 Ma. Whether this field arose by dynamo processes in a small iron core of about 300 km radius, which was inferred from the convection theory and is compatible with the now known value of the moment of inertia factor, or whether it was a permanent magnetization of the deep interior produced by a primeval solar system magnetic field must await further understanding of the early thermal history of the Moon. Thermal convection is seen as an essential basis for understanding the thermal history of the Moon, the traces of tectonic evidence in the lithospheric shell and the history of the magnetic field.

scholarly journals Lunar Magnetism

1977 ◽  
Vol 4 (1) ◽  
pp. 191-193
Author(s):  
S.K. Runcorn
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Iron Core ◽  
Low Grade ◽  
The Moon ◽  
Magnetic Studies ◽  
Steady Magnetic Field ◽  
The Stability ◽  
Time Of Origin

It was not generally anticipated by lunar scientists that the Moon rocks would prove to possess a natural remanent magnetization because the absence of a present field had already been demonstrated and it was almost universally believed that the Moon did not possess an iron core in which such a field could be generated. Consequently the initial investigation of Apollo 11 rocks was directed towards the use of rock magnetic studies as an adjunct to petrological examination. One of the most notable findings of the Apollo programme was the demonstration of the existence of a natural remanent magnetization (NRM) in Apollo 11 lavas and breccias. Experiments on the stability of the NRM enabled it to be concluded that the rocks were already magnetized when they were on the Moon. This conclusion was soon corroborated by the discovery of the existence of a steady magnetic field at the Apollo 12 site of the magnitude expected from the intensity of the NRM of about 36 γ (in addition to the field fluctuating solar wind. It was reasoned from this early work that the natural remanent magnetization had been acquired at the time of origin of the rocks or at least in their early history and a case was made out that this was a thermoremanent magnetization acquired as the lava flows cooled from magma flowing into the mare basin and as the high grade breccias cooled after the impacts. The origin of the natural remanent magnetization of the low grade breccias is more problematic and the role of other kinds of remanent magnetization processes has been investigated, particularly the effect of shock.

The early magnetic field and primeval satellite system of the Moon: clues to planetary formation

1994 ◽  
Vol 349 (1690) ◽  
pp. 181-196 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Anomalies ◽  
Satellite System ◽  
Iron Core ◽  
Planetary Formation ◽  
The Moon ◽  
The Core ◽  
Basin Formation ◽  
The Mean ◽  
The Moment

From the stable remanent magnetization of the Apollo igneous rocks and high-grade breccias the existence of a primeval lunar magnetic field was inferred. The palaeointensities of the samples rise rapidly to a maximum at 3.9 Ga, then decrease exponentially to 3.2 Ga, strongly suggesting that the Moon had a field generated in a core, the existence of which was inferred from its non-hydrostatic figure. Modelling of the Apollo 15 and 16 subsatellite magnetic anomalies, by P. J. Coleman, L. L. Hood and C. T. Russell, gave palaeomagnetic directions of crustal strata. This enabled N pole positions to be calculated, which were empirically found to form three bipolar groups, the mean poles of which define (on the core dynamo hypothesis) three axes of rotation different from the present. These were dated as Pre-Nectarian, Lower Nectarian, and Upper Nectarian-Imbrian. Multi-ring basins of these ages were found to lie close to the corresponding palaeo-equators. The impacting bodies were therefore satellites, not asteroids or comets. Their velocities, before collision, can be shown (from basin asymmetries) to be nearly equatorial. The consequent changes in the moment of inertia tensor by basin formation caused these successive reorientations of the Moon relative to its axis of rotation in space. The three mean poles form a 90° spherical triangle. The explanation is that the Moon had three satellites: the orbits of each decayed, they broke up at the Roche limit into smaller bodies, which produced impact basins near the equator. The Moon then reorientated according to Euler’s principle before the next group of impacts. Lunar palaeomagnetism, and especially the inferences that the Moon has an iron core that segregated late and had a primeval satellite system, may provide important constraints on theories of lunar and planetary formation.

Evaluation of concomitant gynecological pathology in group of patients of reproductive age with tumors and tumor formations

2020 ◽  
pp. 10-14
Author(s):  
N. V. Spiridonova ◽  
A. A. Demura ◽  
V. Yu. Schukin
Keyword(s):  
Diagnostic Errors ◽  
Ovarian Tumors ◽  
Reproductive Age ◽  
Women Of Reproductive Age ◽  
Predisposing Factor ◽  
Ovarian Tumours ◽  
Preoperative Diagnostic ◽  
Neoplastic Process ◽  
History Of ◽  
The Moment

According to modern literature, the frequency of preoperative diagnostic errors for tumour-like formations is 30.9–45.6%, for malignant ovarian tumors is 25.0–51.0%. The complexity of this situation is asymptomatic tumor in the ovaries and failure to identify a neoplastic process, which is especially important for young women, as well as ease the transition of tumors from one category to another (evolution of the tumor) and the source of the aggressive behavior of the tumor. The purpose of our study was to evaluate the history of concomitant gynecological pathology in a group of patients of reproductive age with ovarian tumors and tumoroid formations, as a predisposing factor for the development of neoplastic process in the ovaries. In our work, we collected and processed complaints and data of obstetric and gynecological anamnesis of 168 patients of reproductive age (18–40 years), operated on the basis of the Department of oncogynecology for tumors and ovarian tumours in the Samara Regional Clinical Oncology Dispensary from 2012 to 2015. We can conclude that since the prognosis of neoplastic process in the ovaries is generally good with timely detection and this disease occurs mainly in women of reproductive age, doctors need to know that when assessing the parity and the presence of gynecological pathology at the moment or in anamnesis, it is not possible to identify alarming risk factors for the development of cancer in the ovaries.

The Goal of the Moment (Summary of the Lecture Delivered by Ivan Ilyin in May 1917)

2019 ◽  
Vol 60 ◽  
pp. 424-428
Author(s):  
Alexandra I. Vakulinskaya
Keyword(s):  
The State ◽  
October Revolution ◽  
Legal Consciousness ◽  
New Order ◽  
History Of ◽  
The Moment

This publication is devoted to one of the episodes of I. A. Ilyin’s activity in the period “between two revolutions”. Before the October revolution, the young philosopher was inspired by the events of February 1917 and devoted a lot of time to speeches and publications on the possibility of building a new order in the state. The published archive text indicates that the development of Ilyin’s doctrine “on legal consciousness” falls precisely at this tragic moment in the history of Russia.

scholarly journals Interpreting Locked Photographic Data: The Case of Apollo 17 Photo GPN-2000-00113

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Pyrrhon Amathes ◽  
Paul Christodoulides
Keyword(s):  
Experimental Data ◽  
Computer Simulations ◽  
The Moon ◽  
Geometrical Analysis ◽  
Apparent Position ◽  
Apollo Program ◽  
The Earth ◽  
Novel Approach ◽  
The World ◽  
The Moment

Photography can be used for pleasure and art but can also be used in many disciplines of science, because it captures the details of the moment and can serve as a proving tool due to the information it preserves. During the period of the Apollo program (1969 to 1972), the National Aeronautics and Space Administration (NASA) successfully landed humans on the Moon and showed hundreds of photos to the world presenting the travel and landings. This paper uses computer simulations and geometry to examine the authenticity of one such photo, namely Apollo 17 photo GPN-2000-00113. In addition, a novel approach is employed by creating an experimental scene to illustrate details and provide measurements. The crucial factors on which the geometrical analysis relies are locked in the photograph and are: (a) the apparent position of the Earth relative to the illustrated flag and (b) the point to which the shadow of the astronaut taking the photo reaches, in relation to the flagpole. The analysis and experimental data show geometrical and time mismatches, proving that the photo is a composite.

scholarly journals Decolonization and the aesthetics of disorder: Naipaul, Evaristo, Boland

2021 ◽  
pp. 002198942199605
Author(s):  
Matthew Whittle
Keyword(s):  
European History ◽  
Resistance Movements ◽  
Eavan Boland ◽  
History Of ◽  
Paul Gilroy ◽  
Orderly Transition ◽  
The Moment ◽  
Bear Witness ◽  
Formal Features

Decolonization is presented in dominant accounts as an orderly transition and not the culmination of anticolonial resistance movements. This in turn contributes to what Paul Gilroy terms an endemic “post-imperial melancholia” across contemporary European nations and the removal of empire and its demise from understandings of European history. Drawing on Bill Schwarz’s reconceptualization of a Fanonian commitment to disorder, this article focuses on Britain’s history of colonialism and post-imperial immigration and argues for the mapping of a disorderly aesthetics in works by V. S. Naipaul, Bernardine Evaristo, and Eavan Boland. The three formal features of non-linearity, polyvocality, and environmental imagery enable these writers to bear witness to the complex histories of empire, transatlantic slavery, decolonization, and immigration from the colonial “margins”. These “aesthetics of disorder” counter a dominant narrative of decolonial order and challenge conceptions of British exceptionalism that were reinforced at the moment of imperial decline.

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