Introductory remarks

1994 ◽  
Vol 349 (1690) ◽  
pp. 169-170
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Royal Society ◽  
Lunar Regolith ◽  
The Moon ◽  
Global Magnetic Field ◽  
The Subject ◽  
Planetary Missions ◽  
Speculative Hypothesis ◽  
First Time

This year marks not only the twenty-fifth anniversary of the first manned landing on the Moon ( Apollo 11 ) but also the thirty-fifth anniversary of the first planetary missions. The latter was the Soviet Luna 1 and 2 carrying magnetometers to test whether the Moon possessed a global magnetic field. Luna 1 passed the Moon but Luna 2 crash landed, both showed that the Moon had no magnetic field as large as 50 or 100 y (1 y = 10 -5 G = 10 -9 T). Such an experiment had been proposed by S. Chapman ( Nature 160, 395 (1947)) to test a speculative hypothesis concerning magnetic fields of cosmic bodies by P. M. S. Blackett ( Nature 159, 658 (1947)). Chapman’s suggestion was greeted by general amusement: 12 years later it was accomplished. Also two years after the launch of Sputnik 1 in 1957, Luna 3 was launched and for the first time viewed the far side of the Moon on 9 October, 1959. Laboratories from many countries were invited by NASA to take part in the analysis of rocks returned from the Apollo missions and later from the Soviet automated return of cores from the lunar regolith. British laboratories were very active in this work, and a review of the results of the new understanding of the Moon as a result of space missions formed the subject of a Royal Society Discussion Meeting in 1975 (published in Phil. Trans. R. Soc. Lond . A 285). British laboratories received samples from the automated Soviet missions that took cores from the regolith and returned them to Earth. Work on Luna 16 and 20 samples were published in Phil. Trans. R. Soc. Lond . A 284 131-177 (1977) and on Luna 24 in Phil. Trans. R. Soc. Lond . A 297 1-50 (1979).

The lunar dynamo

Science ◽  
2014 ◽  
Vol 346 (6214) ◽  
pp. 1246753 ◽  
Author(s):  
Benjamin P. Weiss ◽  
Sonia M. Tikoo
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
The Moon ◽  
Planetary Interiors ◽  
Mechanical Stirring ◽  
Lunar Rocks ◽  
Order Of Magnitude ◽  
Global Magnetic Field ◽  
Dynamo Process ◽  
Inductive Generation

The inductive generation of magnetic fields in fluid planetary interiors is known as the dynamo process. Although the Moon today has no global magnetic field, it has been known since the Apollo era that the lunar rocks and crust are magnetized. Until recently, it was unclear whether this magnetization was the product of a core dynamo or fields generated externally to the Moon. New laboratory and spacecraft measurements strongly indicate that much of this magnetization is the product of an ancient core dynamo. The dynamo field persisted from at least 4.25 to 3.56 billion years ago (Ga), with an intensity reaching that of the present Earth. The field then declined by at least an order of magnitude by ∼3.3 Ga. The mechanisms for sustaining such an intense and long-lived dynamo are uncertain but may include mechanical stirring by the mantle and core crystallization.

scholarly journals Absence of a long-lived lunar paleomagnetosphere

2021 ◽  
Vol 7 (32) ◽  
pp. eabi7647
Author(s):  
John A. Tarduno ◽  
Rory D. Cottrell ◽  
Kristin Lawrence ◽  
Richard K. Bono ◽  
Wentao Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Lunar Regolith ◽  
The Moon ◽  
Earth’S Magnetosphere ◽  
Solar Winds ◽  
Planetary Bodies ◽  
Earth's Magnetosphere ◽  
Impact Glass ◽  
Magnetic Inclusions

Determining the presence or absence of a past long-lived lunar magnetic field is crucial for understanding how the Moon’s interior and surface evolved. Here, we show that Apollo impact glass associated with a young 2 million–year–old crater records a strong Earth-like magnetization, providing evidence that impacts can impart intense signals to samples recovered from the Moon and other planetary bodies. Moreover, we show that silicate crystals bearing magnetic inclusions from Apollo samples formed at ∼3.9, 3.6, 3.3, and 3.2 billion years ago are capable of recording strong core dynamo–like fields but do not. Together, these data indicate that the Moon did not have a long-lived core dynamo. As a result, the Moon was not sheltered by a sustained paleomagnetosphere, and the lunar regolith should hold buried 3He, water, and other volatile resources acquired from solar winds and Earth’s magnetosphere over some 4 billion years.

scholarly journals Further note on the influence of a magnetic field of radiation frequency

1897 ◽  
Vol 61 (369-377) ◽  
pp. 413-415
Keyword(s):  
Magnetic Field ◽  
Royal Society ◽  
Ruled Surface ◽  
Radius Of Curvature ◽  
Radiation Frequency ◽  
The Subject ◽  
The One

Referring to a former communication of mine, on the subject of Zeeman’s discovery, printed on page 513 of the ‘Proceedings of the Royal Society ’for February 11 this year, vol. 60, No. 367, I wish to add an observation to those previously recorded, as I have recently acquired a concave Rowland grating (3½ X 1½-inch ruled surface, 14,438 lines to inch, 10 feet radius of curvature, being the one used by Mr. George Higgs), of which the spectra of the first and third orders on one side are very satisfactory.

Degenerate induced magnetospheres

2020 ◽  
Author(s):  
Stas Barabash ◽  
Andrii Voshchepynets ◽  
Mats Holmström ◽  
Futaana Yoshifumi ◽  
Robin Ramstad
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Field ◽  
Solar Wind Plasma ◽  
Stellar Winds ◽  
Ionospheric Currents ◽  
Magnetic Barrier ◽  
Atmospheric Escape ◽  
The Subject

<p>Induced magnetospheres of non-magnetized atmospheric bodies like Mars and Venus are formed by magnetic fields of ionospheric currents induced by the convective electric field E = - V x B/c of the solar wind. The induced magnetic fields create a magnetic barrier which forms a void of the solar wind plasma, an induced magnetosphere. But what happens when the interplanetary magnetic field is mostly radial and the convective field E ≈ 0? Do a magnetic barrier and solar wind void form? If yes, how such a degenerate induced magnetosphere work? The question is directly related to the problem of the atmospheric escape due to the interaction with the solar and stellar winds. The radial interplanetary magnetic field in the inner solar system is typical for the ancient Sun conditions and exoplanets on near-star orbits. Also, the radial interplanetary field may provide stronger coupling of the near-planet environment with the solar/stellar winds and thus effectively channels the solar/stellar wind energy to the ionospheric ions. We review the current works on the subject, show examples of degenerate induced magnetospheres of Mars and Venus from Mars Express, Venus Express, and MAVEN measurements and hybrid simulations, discuss physics of degenerate induced magnetospheres, and impact of such configurations on the escape processes.</p>

Some aspects of the physics of the Moon

1974 ◽  
Vol 336 (1604) ◽  
pp. 11-33 ◽  
Keyword(s):  
The Moon ◽  
Geological Time ◽  
Newtonian Theory ◽  
Famous Paper ◽  
The Subject ◽  
Internal Distribution ◽  
A New Technique ◽  
Principles Of Geology ◽  
First Time ◽  
Impact Origin

The development of the study of the Moon falls into three distinct phases. The Moon’s orbit provided a critical test of Newtonian theory, and observation of the motion of the Moon was a central problem in astronomy for over 2½ centuries. The discrepancies between this so-called ‘theory of the Moon’ and its observed motion yielded most important results: the secular and irregular changes in the Earth’s rotation rate, the evolution of the Moon’s orbit through geological time and the internal distribution of density within the Moon. The subject of the Moon’s motion remains today a lively one with many unsolved problems: laser ranging to the Moon provides a new technique for their solution. The study of the evolution of the Moon’s surface started with the famous paper by G. K. Gilbert in 1893 when, for the first time, clear evidence was produced that the craters had an impact origin. The recognition that the Moon’s surface is extremely old- little changed because of the absence of the forces of erosion so important in the terrestrial biosphere-provided a strong impetus for the develop­ment of the accretion theory of the origin of the Earth and planets. From the study of the frequency distribution of craters, dating of the lunar surface has developed and the understanding of the evolution of the surface much improved by the application of the principles of geology.

scholarly journals Dynamo-generated magnetic fields in fast rotating single giants

2008 ◽  
Vol 4 (S259) ◽  
pp. 433-434 ◽  
Author(s):  
Renada Konstantinova-Antova ◽  
Michel Aurière ◽  
Klaus-Peter Schröder ◽  
Pascal Petit
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Stellar Evolution ◽  
Red Giants ◽  
Good Opportunity ◽  
Early Results ◽  
First Time ◽  
Fast Rotating

AbstractRed giants offer a good opportunity to study the interplay of magnetic fields and stellar evolution. Using the spectro-polarimeter NARVAL of the Telescope Bernard Lyot (TBL), Pic du Midi, France and the LSD technique we began a survey of magnetic fields in single G-K-M giants. Early results include 6 MF-detections with fast rotating giants, and for the first time a magnetic field was detected directly in an evolved M-giant: EK Boo. Our results could be explained in the terms of α–ω dynamo operating in these giants.

scholarly journals Magnetic Field Effect in the Process of Rinsing a Magnetic Separator Matrix

1988 ◽  
Vol 2 (3) ◽  
pp. 119-136
Author(s):  
Jiri Galas
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Circuit Design ◽  
Field Effect ◽  
Magnetic Circuit ◽  
Magnetic Field Effect ◽  
Magnetic Separator ◽  
High Gradient ◽  
First Time

This paper surveys fundamental aspects of the problem of rinsing matrices in high gradient magnetic separators. This is done, for the first time, in terms of the magnetic circuit design. Equations have been constructed to describe the effects of spurious remanent magnetic fields on the rinsing process.

MRE Damping Characteristics Evaluation

2016 ◽  
Vol 699 ◽  
pp. 31-36 ◽  
Author(s):  
Eduard Chirila ◽  
Ionel Chirica ◽  
Doina Boazu ◽  
Elena Felicia Beznea
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Smart Materials ◽  
Magnetorheological Elastomers ◽  
Damping Characteristics ◽  
The Subject ◽  
Energy Absorbing ◽  
The Magnetic Field ◽  
Material Form

The paper addresses the study of the damping characteristics estimation and behaviour of the magnetorheological elastomers (MREs) in the absence of magnetic field. This type of material actively changes the size, internal structure and viscoelastic characteristics under the external influences. These particular composite materials whose characteristics can vary in the presence of a magnetic fields are known as smart materials. The feature which causes the variation of properties in magnetic fields is explained by the existence of polarized particles which change the material form by energy absorbing. Damping is a special characteristic that influences the vibratory of the mechanical system. As an effect of this property is the reducing of the vibration amplitudes by dissipating the energy stored during the vibratory moving. The main characteristic that is based on the determination of the damping coefficient is the energy loss, which is the subject of the present paper. Before to start the characteristics determination in the presence of the magnetic field, it is necessary to study these characteristics in the absence of magnetic field. The MRE specimens have been manufactured and tested under the light conditions (non magnetic field). A special experimental test rig was built to investigate the response of the MRE specimens under the charging force. The experimental results show that the loss energy of the MRE specimen can be determined from the charging-discharging curves versus displacement. The results of the MRE specimen are presented in this paper: MRE with feromagnetic particles not exposed in magnetic field during fabrication.

A Study of the Magnetic Field of the Moon

1962 ◽  
Vol 14 ◽  
pp. 45-52 ◽  
Author(s):  
S. S. Dolginov ◽  
E. G. Eroshenko ◽  
L. I. Zhuzgov ◽  
N. V. Pushkov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
The Moon ◽  
Earth’S Magnetic Field ◽  
Earth's Magnetic Field ◽  
The Magnetic Field

The question as to whether the planets and their satellites possess magnetic fields unavoidably arose in connection with the question as to the origin of the Earth's mágnetic field and the nature of a number of geophysical effects.

XVI. The Bakerian Lecture.— On the radiation of heat from the moon, the law of its absorption by our atmosphere, and of its variation in amount with her phases

1873 ◽  
Vol 163 ◽  
pp. 587-627 ◽  
Keyword(s):  
Royal Society ◽  
Radiant Heat ◽  
The Moon ◽  
Short Series ◽  
The Earth ◽  
Series Of Experiments ◽  
The Subject ◽  
The Law

In the years 1869 and 1870 I communicated to the Royal Society the results of a series of experiments made with the view of determining, if possible, the amount of radiant heat coming to the earth from the moon in various conditions of phase, and the nature of that heat as regards the average refrangibility of the rays. Though more successful than I had at first been led to expect, the imperfect accordance between many of the observations still left much to be desired, and the novelty and importance of the subject appeared sufficient to render it advisable to pursue the investigation with greater care and closer attention to details than had hitherto been deemed necessary. Since the conclusion of the series of observations which form the subject of the second paper above referred to, nothing (with the exception of a short series of observations in August and October 1870, of which mention is made towards the end of this paper) was done towards pursuing the subject till the spring of the following year (1871), when the series of observations which form the subject of the present paper were commenced, the same apparatus (only slightly modified) being used and the same method of observation adopted; but, with the view of obtaining an approximate value of the absorption of the moon’s heat in its passage through our atmosphere, and of rendering possible the satisfactory comparison of observations made at different zenith-distances of the moon, the observations were in many cases carried on at intervals at all possible zenith- distances on the same night, and the most favourable opportunities for observing the moon at very different zenith-distances in various conditions of the atmosphere were not lost.

Sign in / Sign up

Export Citation Format

Share Document