Physical Studies of Asteroids By Polarization of the Light

Curves of polarization are available at present for asteroids Vesta, Ceres, Pallas, Iris, Flora, and Icarus. These curves are compared with those of the satellites of Jupiter and Mercury, the Moon, and Mars. Laboratory simulations had already proved that the Moon's surface behaves like a powder of pulverized basalts; the recent confirmation by direct exploration is proving the significance of the method for remote determination of the surface properties of celestial bodies. The simulation of the Martian surface is found on small grained powders oxidized by ferreous limonite or goethite. New laboratory measurements were conducted to prepare the simulation of the asteroidal surfaces. Samples of the lunar surface returned to Earth provide impact-generated regolith and bare rocks superficially pitted and etched by impacts of the types suggested to be found on asteroidal surfaces; they were analyzed polarimetrically.Preliminary interpretations show that Vesta departs significantly from the other asteroids and cannot be covered by frost deposits or by aggregate cosmic dusts; a regolith-type surface generated by impacts or a coating of cohesive grains is indicated.Ceres, Pallas, and Iris are darker, and their polarizations do not suggest a pure regolithic surface, but cohesive grains or aggregates of dust are indicated.Icarus is 108 times smaller in mass; its polarization authorizes a fluffy, loosely aggregated dust deposit; however, a cometary model with stones embedded in ice is perhaps not ruled out on the basis of the present data.The way in which deep-space missions near the asteroidal belt can improve these results is discussed.

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The Antikythera Mechanism: The oldest mechanical universe in its scientific milieu

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311002225 ◽

2009 ◽

Vol 5 (S260) ◽

pp. 135-148 ◽

Cited By ~ 1

Author(s):

Xenophon Moussas

Keyword(s):

Main Part ◽

Accurate Prediction ◽

The Other ◽

Stationary Points ◽

Analogue Computer ◽

The Sun ◽

The Moon ◽

Celestial Bodies ◽

Celestial Sphere ◽

Astronomical Instrument

AbstractIn this review the oldest known advanced astronomical instrument and dedicated analogue computer is presented, in context. The Antikythera Mechanism a mysterious device, assumed to be ahead of its time, probably made around 150 to 100 BCE, has been found in a 1st century BCE shipwreck near the island of Antikythera in a huge ship full of Greek treasures that were on their way to Rome. The Antikythera Mechanism is a clock-like device made of bronze gears, which looks much more advanced than its contemporary technological achievements. It is based on mathematics attributed to the Hipparchus and possibly carries knowledge and tradition that goes back to Archimedes, who according to ancient texts constructed several automata, including astronomical devices, a mechanical planetarium and a celestial sphere. The Antikythera Mechanism probably had a beautiful and expensive box; looking possibly like a very elaborate miniature Greek Temple, perhaps decorated with golden ornaments, of an elegant Hellenistic style, even perhaps with automatic statuettes, ‘daemons’, functioning as pointers that performed some of its operations. Made out of appropriately tailored trains of gears that enable to perform specialised calculations, the mechanism carries concentric scales and pointers, in one side showing the position of the Sun in the ecliptic and the sky, possibly giving the time, hour of the day or night, like a clock. The position of the Moon and its phase is also shown during the month. On the other side of the Mechanism, having probably the size of a box (main part 32×20×6 cm), are two large spiral scales with two pointers showing the time in two different very long calendars, the first one concerning the eclipses, and lasting 18 years 11 days and 8 hours, the Saros period, repeating the solar and lunar eclipses, and enabling their prediction, and the 19 year cycle of Meton, that is the period the Moon reappears in the same place of the sky, with the same phase. An additional four-year dial shows the year of all Greek Festivities, the so-called ‘games’ (Olympic, Pythian, Isthmian etc). Two additional dials give the Exeligmos, the 54 year and 34 day cycle, which provides a more accurate prediction of eclipses. It is possible that the Mechanism was also equipped with a planetary show display, as three of the planets and their motion (stationary points) are mentioned many times in the manual of the instrument, so it was also a planetarium. From the manual we have hints that the mechanism was probably also an observational instrument, as having instructions concerning a viewfinder and possibly how to orient the viewfinder to pass a sunbeam through it, probably measuring the altitude of the Sun. There are fragmented sentences that probably give instructions on how to move the pointers to set the position of the Sun, the Moon and the planets in their initial places in the ecliptic, on a specific day, or how to measure angular distances between two celestial bodies or their coordinates. This mechanism is definitely not the first one of its kind. The fact that it is accompanied with instructions means that the constructor had in its mind to be used by somebody else and one posits that he made at least another similar instrument.

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Είμαστε μόνοι στο συμπάν; Οι μετεωρίτες δίνουν απαντήσεις;

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.10897 ◽

2016 ◽

Vol 47 (1) ◽

pp. 32

Author(s):

Ι. Μπαζιώτης ◽

L. A. Taylor

Keyword(s):

High Pressures ◽

Geochemical Data ◽

The Moon ◽

Martian Surface ◽

The Earth ◽

Past Life ◽

Celestial Bodies ◽

Meteorite Fall ◽

Event Based ◽

Moon Landing

The humankind, despite the recent technological achievements, does not yet have the ability to carry out routine trips to nearby celestial bodies. However, space science is a reality. The “Apollo” missions, that took place during the period 1969-1972, included the moon landing, the walk of astronauts and collection of valuable samples. Since then, no similar space journey has been carried out. The possibility for future missions such as the return to the Moon or Mars, or to an asteroid (e.g., Vesta), seems small enough to be implemented in the next decades. Nevertheless, nature has the mechanism and procedures to resolve this problem by sending extra-terrestrial rocks in earth in the form of meteorites. Meteorite fall on Earth is a major event, as it reveals important information about the primordial stages of formation of our solar system, or the creation processes of other planets. However, the big question still remains; whether these rocks host or have traces of past life in turn employs researchers in the last twenty years. McKay et al. (1996) studied the meteorite ALH 84001 originating from Mars, claimed for important discoveries such as structures corresponding to nanobacteria. In the current paper, we focus on the origin of Martian meteorites, presenting their complete geological history; from the genesis of their protoliths till their falling to the earth. We attempt to shade light in the understanding of meteorite formation using mineralogical-petrological-geochemical data, and the assignment of timing for each event based upon contemporary geochronological data. Recently, studies of the Martian meteorite Tissint, allegedly discovered structures rich in carbon and oxygen. Furthermore, recent field observations from Curiosity rover, indicates the existence of surface water that flowed once in the past at the Martian surface. We conclude that the planet Mars might not be a "dead" planet. But it turns out that many of the meteorites that reach the Earth, have undergone a complex history which is associated with the development of very high pressures and temperatures on the surface of the planet (e.g., Mars) from which they originate, able to destroy any trace of life before them. After all, we should be very sceptic and evaluate all the possibilities before the acceptance for the existence of life out there.

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Eksistensi ‘Illat dalam Mengukuhkan Teks Hadis-hadis Ru’yat al-Hilāl dan Fungsinya dalam Pengembangan Hukum Islam

Al-Ahkam ◽

10.21580/ahkam.2018.18.2.2352 ◽

2019 ◽

Vol 18 (2) ◽

pp. 161

Author(s):

Busyro Busyro

Keyword(s):

The Other ◽

The Moon ◽

Other Hand ◽

The People ◽

The Law ◽

Modern Era

Ḥisāb and ru’yat always be warm conversations when there is an early determination of Ramadhan and Shawwal. At that time, there are always two camps of scholars in reacting, the scholars who hold on to ḥisāb (calculating the calendar) on one side, and on the other hand hold to ru’yat al-hilāl (seeing the moon directly). This in turn often leads to time differences in setting the beginning of the month among Muslims. With the aim to unite the people in starting their worship, some scholars try to understand the texts of these traditions about ru’yat al-hilāl by trying to find the 'illat (reason) of the laws of hadiths about ru’yat al-hilāl. Their study of the 'illat law resulted in the conclusion that the ru’yat al-hilāl is only a suitable means for the people that time and may not suitable for Muslims in this modern era. Therefore Muslims must use other wasīlah (means) which further guarantee the realization of the purpose of law, namely modern astronomy. The conclusion of the law from the side of the discovery of ‘illat seems to be less suited to the purpose of ta'līl al-aḥkām, is to establish textual texts in addition to discovering the forms of development of the texts.

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The Value of Photoelectric Occultation Timings in Lunar Motion Studies

Highlights of Astronomy ◽

10.1017/s1539299600000630 ◽

1971 ◽

Vol 2 ◽

pp. 587-588 ◽

Cited By ~ 1

Author(s):

Thomas C. Van Flandern

Keyword(s):

The Other ◽

The Moon ◽

Observational Error ◽

Additional Time ◽

Current Application ◽

Error Sources ◽

Lunar Motion ◽

Lunar Ephemeris ◽

Motion Studies

AbstractThe two most important advantages of photoelectric timings of occultations over visual timings are accuracy and freedom from systematic error. The observational error is so small compared with uncertainties in the lunar ephemeris, star positions, limb corrections, and such, that the value of the observations will continue to increase as time goes on and the other error sources are eliminated.A recent result made possible largely by the availability of photoelectric timings over the last 20 yr is a new value for the secular acceleration of the Moon, with corresponding consequences for the Ephemeris Time scale.An important current application for simultaneous photoelectric and visual observations is the determination of ‘personal equation’ for the visual observers. Experiments so far indicate the visual observers require a minimum of 0.1 sec to detect that an event has occurred, plus additional time to react to it; hence, typical personal equations are around 0.4 sec.

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Satellites and Pluto

Photochemistry of Planetary Atmospheres ◽

10.1093/oso/9780195105018.003.0009 ◽

1999 ◽

Author(s):

Yuk L. Yung ◽

William B. DeMore

Keyword(s):

Solar System ◽

The Other ◽

The Moon ◽

Small Bodies ◽

Planetary Body ◽

Galilean Moons ◽

Satellites Of Jupiter ◽

Tidal Heating ◽

Pioneer 10 ◽

Active Volcanoes

The presence of an atmosphere on a small planetary body the size of the Moon is surprising. Loss of material by escape would have depleted the atmosphere over the age of the solar system. Since these objects are not large enough to possess, or to sustain for long, a molten core, continued outgassing from the interior is not expected. However, it is now known that four small bodies in the outer solar system possess substantial atmospheres: lo, Titan, Triton, and Pluto. These atmospheres range from the very tenuous on lo (of the order of a nanobar) to the very massive on Titan (of the order of a bar). The atmospheric pressures on Triton and Pluto are of the order of 10 μbar. Perhaps the most interesting questions about these atmospheres concern their unusual origin and their chemical evolution. lo is the innermost of the four Galilean satellites of Jupiter, the other three being Ganymede, Europa, and Callisto. All the Galilean moons are comparable in size, but there is no appreciable atmosphere on the other moons. The first indications that lo possesses an atmosphere came in 1974 with the discovery of sodium atoms surrounding the satellite and the detection of a well-developed ionosphere from the Pioneer 10 radio occultation experiment. The Voyager encounter in 1979 established the existence of active volcanoes as well as SOa gas. These are the only extraterrestrial active volcanoes discovered to date, and they owe their existence to a curious tidal heating mechanism associated with the 2:1 resonance between the orbits of lo and Europa.

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MAPPING OF INNER AND OUTER CELESTIAL BODIES USING NEW GLOBAL AND LOCAL TOPOGRAPHIC DATA DERIVED FROM PHOTOGRAMMETRIC IMAGE PROCESSING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b4-411-2016 ◽

2016 ◽

Vol XLI-B4 ◽

pp. 411-415

Author(s):

I. P. Karachevtseva ◽

A. A. Kokhanov ◽

J. F. Rodionova ◽

A.Yu. Zharkova ◽

M.S. Lazareva

Keyword(s):

Local Level ◽

Control Point ◽

Three Dimensional ◽

Super Resolution ◽

The Moon ◽

Satellites Of Jupiter ◽

Celestial Bodies ◽

Terrestrial Planetary Bodies ◽

Solar System Exploration ◽

Global And Local

New estimation of fundamental geodetic parameters and global and local topography of planets and satellites provide basic coordinate systems for mapping as well as opportunities for studies of processes on their surfaces. The main targets of our study are Europa, Ganymede, Calisto and Io (satellites of Jupiter), Enceladus (a satellite of Saturn), terrestrial planetary bodies, including Mercury, the Moon and Phobos, one of the Martian satellites. In particular, based on new global shape models derived from three-dimensional control point networks and processing of high-resolution stereo images, we have carried out studies of topography and morphology. As a visual representation of the results, various planetary maps with different scale and thematic direction were created. For example, for Phobos we have produced a new atlas with 43 maps, as well as various wall maps (different from the maps in the atlas by their format and design): basemap, topography and geomorphological maps. In addition, we compiled geomorphologic maps of Ganymede on local level, and a global hypsometric Enceladus map. Mercury’s topography was represented as a hypsometric globe for the first time. Mapping of the Moon was carried out using new images with super resolution (0.5-1 m/pixel) for activity regions of the first Soviet planetary rovers (Lunokhod-1 and -2). New results of planetary mapping have been demonstrated to the scientific community at planetary map exhibitions (Planetary Maps Exhibitions, 2015), organized by MExLab team in frame of the International Map Year, which is celebrated in 2015-2016. Cartographic products have multipurpose applications: for example, the Mercury globe is popular for teaching and public outreach, the maps like those for the Moon and Phobos provide cartographic support for Solar system exploration.

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MAPPING OF INNER AND OUTER CELESTIAL BODIES USING NEW GLOBAL AND LOCAL TOPOGRAPHIC DATA DERIVED FROM PHOTOGRAMMETRIC IMAGE PROCESSING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b4-411-2016 ◽

2016 ◽

Vol XLI-B4 ◽

pp. 411-415

Author(s):

I. P. Karachevtseva ◽

A. A. Kokhanov ◽

J. F. Rodionova ◽

A.Yu. Zharkova ◽

M.S. Lazareva

Keyword(s):

Local Level ◽

Control Point ◽

Three Dimensional ◽

Super Resolution ◽

The Moon ◽

Satellites Of Jupiter ◽

Celestial Bodies ◽

Terrestrial Planetary Bodies ◽

Solar System Exploration ◽

Global And Local

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XV. — Researches in physical astronomy

Philosophical Transactions of the Royal Society of London ◽

10.1098/rstl.1831.0016 ◽

1831 ◽

Vol 121 ◽

pp. 231-282

Keyword(s):

Differential Equations ◽

The Other ◽

Lunar Theory ◽

System Of Equations ◽

Planetary Theory ◽

The Moon ◽

Celestial Bodies ◽

Independent Variable ◽

The Mean ◽

The One

The method pursued by Clairaut in the solution of this important problem of Physical Astronomy, consists in the integration of the differential equations furnished by the principles of dynamics, upon the hypothesis that in the gravitation of the celestial bodies the force varies inversely as the square of the distance, and in which the true longitude of the moon is the independent variable ; the time is thus obtained in terms of the true longitude, and by the reversion of series the longitude is afterwards obtained in terms of the time, which is necessary for the purpose of forming astronomical tables. But while on the one hand this method possesses the advantage, that the disturbing function can be developed with somewhat greater facility in terms of the true longitude of the moon than in terms of the mean longitude, yet on the other hand, the differential equations in which the true longitude is the independent variable are far more complicated than those in which the time is the independent variable. The latter equations are used in the planetary theory ; so that the method of Clairaut has the additional inconvenience, that while the lunar theory is a particular case of the problem of the three bodies, one system of equations is used in this case, and another in the case of the planets. The method of Clairaut has been adopted, however, by Mayer, by Laplace, and by M. Damoiseau. The last-mentioned author has arranged his results with remarkable clearness, so that any part of his processes may be easily verified by any one who does not shrink from this gigantic undertaking; and the immense labour which this method requires, when all sensible quantities are retained, may be seen in his invaluable memoir. Mr. Brice Bronwin has recently communicated to the Society a lunar theory, in which the same method is adopted.

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Determination of the lattice translation across {110} APBs in GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105060 ◽

1988 ◽

Vol 46 ◽

pp. 600-601

Author(s):

D.R. Rasmussen ◽

N.-H. Cho ◽

C.B. Carter

Keyword(s):

Grain Boundaries ◽

Lower Energy ◽

Antiphase Boundary ◽

The Other ◽

Boundary Structure ◽

Interface Plane ◽

Inversion Symmetry ◽

High Angle ◽

Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

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Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108799 ◽

1978 ◽

Vol 36 (1) ◽

pp. 330-331

Author(s):

Y. Ishida ◽

H. Ishida ◽

K. Kohra ◽

H. Ichinose

Keyword(s):

High Order ◽

Simulation Technique ◽

The Other ◽

Image Simulation ◽

Diffraction Vector ◽

Burgers Vector ◽

Weak Beam ◽

Beam Image ◽

Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

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