Virial oscillations of celestial bodies: V. The structure of the potential and kinetic energies of a celestial body as a record of its creation history

1996 ◽  
Vol 64 (3) ◽  
pp. 167-183 ◽  
Author(s):  
V. I. Ferronsky ◽  
S. A. Denisik ◽  
S. V. Ferronsky
Keyword(s):  
Celestial Body ◽  
Celestial Bodies

scholarly journals Reference frame and map projection for irregular shaped celestial bodies

2020 ◽  
Vol 2 ◽  
pp. 1-2
Author(s):  
Krisztián Kerkovits ◽  
Tünde Takáts
Keyword(s):  
Celestial Body ◽  
Reference Frame ◽  
Reference Frames ◽  
Surfaces Of Revolution ◽  
Map Projection ◽  
Map Projections ◽  
Ellipsoid Of Revolution ◽  
Celestial Bodies ◽  
Best Fitting ◽  
Comet 67P

Abstract. Recent advancements of technology resulted in greater knowledge of the Solar System and the need for mapping small celestial bodies significantly increased. However, creating a good map of such small objects is a big challenge for the cartographer: they are usually irregular shaped, the usual reference frames like the ellipsoid of revolution is inappropriate for their approximation.A method is presented to develop best-fitting irregular surfaces of revolution that can approximate any irregular celestial body. (Fig. 1.) Then a simple equal-area map projection is calculated to map this reference frame onto a plane. The shape of the resulting map in this projection resembles the shape of the original celestial body.The usefulness of the method is demonstrated on the example of the comet 67P/Churyumov-Gerasimenko. This comet has a highly irregular shape, which is hard to map. Previously used map projections for this comet include the simple cylindrical, which greatly distorts the surface and cannot depict the depressions of the object. Other maps used the combination of two triaxial ellipsoids as the reference frame, and the gained mapping had low distortion but at the expense of showing the tiny surface divided into 11 maps in different complicated map projections (Nyrtsov et. al., 2018). On the other hand, our mapping displays the comet in one single map with moderate distortion and the shape of the map frame suggests the original shape of the celestial body (Fig. 2. and 3.).

scholarly journals Once more on the origin of Semetic and Greek star names: an astromonic-etymological approach updated

2005 ◽  
Vol 09 (01) ◽  
pp. 3-43
Author(s):  
Gennadij Kurtik ◽  
Alexander Militarev
Keyword(s):  
Celestial Body ◽  
The Other ◽  
Historical Background ◽  
Semitic Languages ◽  
Greek Culture ◽  
Celestial Bodies ◽  
Greek World ◽  
Modern Astronomy

The contribution is a new version of the paper "From Mesopotamia to Greece: to the Origin of Semitic and Greek Star Names" once written by a Sumerologist (L.Bobrova) and etymologist (A. Militarev), and recently revised, updated and corrected in most part by a historian of the Mesopotamian astronomy (G. Kurtik). The present paper analyzes Sumerian and Akkadian (Babylonian) names of 34 celestial bodies, and their equivalents in other Semitic languages (Arabic, Hebrew, Syrian Aramaic, and Ge`ez, or ancient Ethiopian) and in Greek and Latin. Its main goal is to demonstrate the importance of Sumerian and Babylonian celestial body names as a source of corresponding terms in other cultures, up to the conventional inventory of modern astronomy, and to reveal four strategies by which other cultures drew ideas for name-giving from the treasury of Mesopotamia's lexicon of celestial bodies. Whereas one of these strategies -- echoing, or full translation, of a Sumero-Akkadian term -- is axiomatic, the other three -- shift of meaning or interpretation of a Sumero-Akkadian term; lexical, or "material" borrowing; and, especially, folk etymology, or misinterpretation -- are understudied and practically unnoticed. The authors do not focus on such complicated matters as a historical background of Mesopotamian influence, direct or indirect, on Greek culture; a direction and routes of inter-borrowing between different speaking areas other than Akkadian and their contacts with the Greek world; a chronology of all kinds of cultural contacts and influences; probable connections between the early pre-Islamic Arabic and Babylonian traditions; or the problem of identification of Mesopotamian constellation and stars. However, the data presented may give a certain impulse to further investigation of these matters, while feasible etymologies and relations established between names can even throw some light upon debatable identification cases.

scholarly journals The Correlation between Rotational Gravity and Magnetic Field of Celestial Body

2020 ◽  
Author(s):  
Ying-Qiu Gu
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Celestial Body ◽  
Flux Line ◽  
Dynamo Model ◽  
Internal Variables ◽  
Physical Parameters ◽  
Origin And Evolution ◽  
Celestial Bodies ◽  
The Magnetic Field

The magnetic field of the earth plays an important role in the ecosystem, and the magnetic field of celestial bodies is also important in the formation of cosmic large-scale structures, but the origin and evolution of the celestial magnetic field is still an unresolved mystery. Many hypotheses to explain the origin have been proposed, but there are some insurmountable difficulties for each one. At present, the theory widely accepted in scientific society is the dynamo model, it says that, the movement of magnetofluid inside celestial bodies, which can overcome the Ohmic dissipative effect and generate persistent weak electric current and macroscopic magnetic field. However, this model needs an initial seed magnetic field, and the true values of many physical parameters inside the celestial body are difficult to obtain, and there is no stable solution to the large range of fluid motion. These are all difficulties for the dynamo model. Furthermore, it is difficult for the dynamo to explain the correlation between the dipole magnetic field and angular momentum of a celestial body. In this paper, by calculating the interaction between spin of particles and gravity of celestial body according to Clifford algebra, we find that a rotational celestial body provides a field $\Omega^\alpha$ for spins, which is similar to the magnetic field of a dipole, and the spins of charged particles within the celestial body are arranged along the flux line of $\Omega^\alpha$, then a macroscopic magnetic field is induced. The calculation shows that the strength of $\Omega^\alpha$ is proportional to the angular momentum of the celestial body, which explains the correlation between the magnetic intensity and angular momentum. The results of this paper suggest that further study of the effects of internal variables such as density, velocity, pressure and temperature of a celestial body on $\Omega^\alpha$ may provide some new insights into the origin and evolution of celestial magnetic field.

Astronomical position without observed altitude of the celestial body

2017 ◽  
Vol 71 (2) ◽  
pp. 454-466
Author(s):  
Zvonimir Lušić
Keyword(s):  
Information System ◽  
Celestial Body ◽  
Precise Measurement ◽  
Dead Reckoning ◽  
Great Circle ◽  
Position Determination ◽  
Straight Line ◽  
Electronic Chart ◽  
Celestial Bodies ◽  
The Dead

The basis of all recommended methods for obtaining position by using celestial bodies is the known altitude of the celestial body being observed. Accordingly, it is necessary to have a sextant, classic or with an artificial horizon, or some other device that can measure altitude. However, there is a way to obtain position using astronomical navigation without determining the altitude of a celestial body, and this method will be analysed in this paper. The introduced method requires only precise measurement of the azimuth, and is based on determining two positions close to the dead reckoning position and lying on the isoazimuthal curve, i.e. a curve of the same great circle azimuths of a celestial body. Furthermore, the model assumes that a part of this curve, between the selected positions, can be replaced by a straight line. Special attention will be given to the analysis of errors of the line of position for various azimuth errors and various dead reckoning (assumed) positions. It will also be shown how a modern Electronic Chart Display and Information System (ECDIS) can help in approximate position determination, knowing only the azimuths of celestial bodies.

On the Identity of Shang Di and the Origin of the Concept of a Celestial Mandate (TIAN MING)

Early China ◽  
2007 ◽  
Vol 31 ◽  
pp. 1-46 ◽  
Author(s):  
Sarah Allan
Keyword(s):  
Celestial Body ◽  
The Other ◽  
Zhou Dynasty ◽  
Celestial Bodies ◽  
Mandate Of Heaven ◽  
The One

This article reexamines the hypotheses of Guo Moruo and H.G. Creel that Shang Di was the high god of the Shang and Tian, that of the Zhou. It proposes that Shang Di was originally the spirit of the pole star. As such, it was the one celestial body which was higher than the ten suns, with whom the Shang ancestors were identified. Tian was not a high god, but quite literally, the sky. The sky was the location of the Shang Di and the other ancestral spirits, so it came to serve as a euphemism for Shang Di or, more broadly, for Shang Di and all the celestial phenomena and spirits who were under his aegis. The primary distinction between the Shang and Zhou was not that Shang Di was particular to the Shang, but that the Shang rulers identified themselves with the ten suns. Shang Di, as the pole star, was acknowledged by both Shang and Zhou as the highest of the spirits. Tian, as the sky, was understood primarily as the celestial bodies that inhabit it. As in later time, the sky was a spiritual force associated with patterns of time, which were revealed in the movements of the celestial bodies. Thus, the originaltian ming(“celestial mandate” or “mandate of heaven”) was, quite literally, an astronomical sign, a “command” seen in the sky during the reign of Wen, whose son Wu founded the Zhou Dynasty.

Dynamics of Landing a Spacecraft on a Small Celestial Body with Conditional Operation of Pinch Engines

2015 ◽  
Vol 798 ◽  
pp. 125-128 ◽  
Author(s):  
Dan He Chen ◽  
Victor P. Kazakovtsev ◽  
Vsevolod V. Koryanov
Keyword(s):  
Gravitational Field ◽  
Celestial Body ◽  
Working Conditions ◽  
Optimal Time ◽  
Minimum Value ◽  
Engine Thrust ◽  
Celestial Bodies ◽  
The Stability

The problem of the dynamics of space lander landing on the surface of a celestial body with small gravitational field is considered in this paper. This report presents a sustainable solution to the problem of landing on a small celestial body based on the use of special pinch engines. The thrust value of pinch engines is considered to be constant in process of operation. The optimal time of inclusion of works of pinch engines, working conditions to ensure the stability of landing lander on the surface of small celestial bodies is defined in this paper, and influence of the thrust value of pinch engines on the stability of landing also investigated in this paper. The minimum value of the ratio of engine thrust to weight of space lander, at which make landing reliable and stable is presented.

Tensegrity Heat Shield for Atmospheric Entry Through Celestial Bodies

2016 ◽  
Author(s):  
Shaurya Deep Chopra ◽  
Mircea Teodorescu ◽  
Steven Lessard ◽  
Adrian Agogino ◽  
Vytas SunSpiral
Keyword(s):  
Celestial Body ◽  
Flexible Structures ◽  
Vital Role ◽  
Heat Shield ◽  
Space Vehicles ◽  
Tensegrity Structures ◽  
Drag Forces ◽  
Rigid Rods ◽  
Heat Shields ◽  
Celestial Bodies

Heat shields play a vital role in protecting space vehicles during the atmosphere reentry. Therefore, they are essential for space vehicles, and better designed heat shields will vastly improve the ability both of robots and humans to explore extraterrestrial destinations. The main goal of the current paper is to investigate the feasibility of designing, building and deploying a tensegrity-based heat shield, which would withstand the atmospheric reentry of a low gravity and dense atmosphere celestial body (such as Titan), where the reentry accelerations and therefore, drag forces, will be lower than in the case of a high gravity planet (e.g., Earth or Mars). The paper is a preliminary study, which investigates the parameters that would be helpful in designing tensegrity-based heat shields. We explore the dynamics of entry and how the atmospheric forces interact with the heat shield. Tensegrity structures consist of tension elements used in conjunction with rigid rods which are actuated by changing the lengths of the tension elements. The advantage of the proposed approach versus the traditional one (rigid heat shields) is that tensegrity structures are flexible structures able to adapt the shape to obtain an optimal reentry configuration. The proposed heat shield will be able to fold in a small space during transport (e.g., to the target celestial body), unfold when the target is reached and provide additional mobility for an optimal reentry pattern. However, to achieve a deployable configuration, the tensegrity structure must withstand significant dynamics and thermal loads. We will use NASA Tensegrity Robotics Toolkit (NTRT) to simulate the structural designs of the heat shield as well as for designing the controllers.

Symmetric Multistep Methods Revisited: II. Numerical Experiments

1999 ◽  
Vol 173 ◽  
pp. 309-314 ◽  
Author(s):  
T. Fukushima
Keyword(s):  
Multistep Methods ◽  
Computational Time ◽  
Integration Time ◽  
Implicit Methods ◽  
Symmetric Methods ◽  
Celestial Bodies ◽  
The Stability ◽  
Predictor Corrector ◽  
Symmetric Multistep Methods ◽  
Integration Errors

AbstractBy using the stability condition and general formulas developed by Fukushima (1998 = Paper I) we discovered that, just as in the case of the explicit symmetric multistep methods (Quinlan and Tremaine, 1990), when integrating orbital motions of celestial bodies, the implicit symmetric multistep methods used in the predictor-corrector manner lead to integration errors in position which grow linearly with the integration time if the stepsizes adopted are sufficiently small and if the number of corrections is sufficiently large, say two or three. We confirmed also that the symmetric methods (explicit or implicit) would produce the stepsize-dependent instabilities/resonances, which was discovered by A. Toomre in 1991 and confirmed by G.D. Quinlan for some high order explicit methods. Although the implicit methods require twice or more computational time for the same stepsize than the explicit symmetric ones do, they seem to be preferable since they reduce these undesirable features significantly.

scholarly journals III. On the nature and construction of the sun and fixed stars

1795 ◽  
Vol 85 ◽  
pp. 46-72 ◽  
Keyword(s):  
Central Body ◽  
Planetary System ◽  
Considerable Progress ◽  
The Sun ◽  
Great Satisfaction ◽  
The Earth ◽  
The World ◽  
Celestial Bodies ◽  
The Universe ◽  
Made In

Among the celestial bodies the sun is certainly the first which should attract our notice. It is a fountain of light that illuminates the world! it is the cause of that heat which main­tains the productive power of nature, and makes the earth a fit habitation for man! it is the central body of the planetary system; and what renders a knowledge of its nature still more interesting to us is, that the numberless stars which compose the universe, appear, by the strictest analogy, to be similar bodies. Their innate light is so intense, that it reaches the eye of the observer from the remotest regions of space, and forcibly claims his notice. Now, if we are convinced that an inquiry into the nature and properties of the sun is highly worthy of our notice, we may also with great satisfaction reflect on the considerable progress that has already been made in our knowledge of this eminent body. It would require a long detail to enumerate all the various discoveries which have been made on this subject; I shall, therefore, content myself with giving only the most capital of them.

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