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At least 19 recordsLinked to original sources
PubMed2005

Lagrange L4/L5 points and the origin of our Moon and Saturn's moons and rings.

The current standard theory of the origin of the Moon is that the Earth was hit by a giant impactor the size of Mars causing ejection of debris from its mantle that coalesced to form the moon; but where did this Mars-sized impactor come from? Isotopic evidence suggests that it came from 1 AU radius in the solar nebula, and computer simulations are consistent with its approaching Earth on a zero-energy parabolic trajectory. How could such a large object form at 1 AU in a quiescent disk of planetesimals without having already collided with the Earth at an earlier epoch before having the chance to grow large? Belbruno and Gott propose that the giant impactor could have formed in a stable orbit from debris at the Earth's Lagrange point L(5) (or L(4)). It would grow quietly by accretion at L(5) (or L(4)), but eventually gravitational perturbations by other growing planetesimals would kick it out into a horseshoe orbit and finally into a chaotic creeping orbit, which Belbruno and Gott show would, with high probability, hit the Earth on a near zero-energy parabolic trajectory. We can see other examples of this phenomenon occurring in the solar system. Asteroid 2002AA29 is in a horseshoe orbit relative to the Earth that looks exactly like the horseshoe orbits that Belbruno and Gott found for objects that had been perturbed from L(4)/L(5). The regular moons of Saturn are made of ice and have the same albedo as the ring particles (ice chunks, plus some dust). We (J. R. Gott, R. Vanderbei, and E. Belbruno) propose that the regular icy moons of Saturn (out to the orbit of Titan), which are all in nearly circular orbits, formed out of a thin disk of planetesimals (ice chunks) rather like the rings of Saturn today only larger in extent. In such a situation formation of objects at L(4)/L(5) might be expected. Indeed, Saturn's moon Dione is accompanied by moons (Helene and Polydeuces) at both L(4) and L(5) Lagrange points, and Saturn's moon Tethys is also accompanied by moons (Telesto and Calypso) at both L(4) and L(5) Lagrange points. Epimetheus is in a horseshoe orbit relative to Janus that is exactly like the horseshoe orbit expected for an object that has been perturbed from a location at L(4)/L(5). We propose that the rings of Saturn visible today are all that remains of this original disk; they lie inside the Roche limit where tidal forces have simply prevented the formation of large moons by accretion. Further out, the icy particles have accumulated into icy moons. Objects in external solar systems on horseshoe orbits (like those of Epimetheus relative to Janus) could be detected by a slow sinusoidal variation with time of the calculated mass of a planet from radial velocity measurements.

Journal Article↗
PubMed2000

Explaining the moon illusion.

An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the horizon moon must be perceived as larger. More recent explanations hold that differences in accommodation or other factors cause the elevated moon to appear smaller. As a result of this illusory difference in size, the elevated moon appears to be more distant than the horizon moon. These two explanations, both based on the geometry of stereopsis, lead to two diametrically opposed hypotheses. That is, a depth interval at a long distance is associated with a smaller binocular disparity, whereas an equal depth interval at a smaller distance is associated with a larger disparity. We conducted experiments involving artificial moons and confirmed the hypothesis that the horizon moon is at a greater perceptual distance. Moreover, when a moon of constant angular size was moved closer it was also perceived as growing smaller, which is consistent with the older explanation. Although Emmert's law does not predict the size-distance relationship over long distances, we conclude that the horizon moon is perceived as larger because the perceptual system treats it as though it is much farther away. Finally, we observe that recent explanations substitute perceived size for angular size as a cue to distance. Thus, they imply that perceptions cause perceptions.

Accommodation, Ocular↗
PubMed2005

Earth-to-Moon low energy transfers targeting L1 hyperbolic transit orbits.

In the frame of the lunar exploration, numerous future space missions will require maximization of payload mass, and simultaneously achieving reasonable transfer times. To fulfill this request, low energy non-Keplerian orbits could be used to reach the Moon instead of high energetic transfers. The low energy solutions can be separated into two main categories depending on the nature of the trajectory approaching the Moon: low energy transit orbits that approach the Moon from the interior equilibrium point L(1) and weak stability boundary transfers that reach the Moon after passing through L(2). This paper proposes an alternative way to exploit the opportunities offered by L(1) transit orbits for the design of Earth-Moon transfers. First, in a neighborhood of the L(1) point, the three-body dynamics is linearized and written in normal form; then the entire family of nonlinear transit orbits is obtained by selecting the appropriate nontrivial amplitudes associated with the hyperbolic part. The L(1)-Earth arc is close to a 5:2 resonant orbit with the Moon, whose perturbations cause the apogee to rise. In a second step, two selected low altitude parking orbits around the Earth and the Moon are linked with the transit orbit by means of two three-body Lambert arcs, solutions of two two-point boundary value problems. The resulting Earth-to-Moon trajectories prove to be very efficient in the Moon captured arc and save approximately 100 m/sec in Deltav cost when compared to the Hohmann transfer. Furthermore, such solutions demonstrate that Moon capture could be obtained in the frame of the Earth-Moon R3BP neglecting the presence of the Sun.

Journal Article↗
PubMed1989

Trauma and the full moon: a waning theory.

There exists a popular belief in the causal relationship between the moon's phase and the incidence of major trauma. In this retrospective study we reviewed 1,444 trauma victims admitted to the hospital during one calendar year. Full moons were defined as three-day periods in the 29.531-day lunar cycle, with the middle day being described in the world almanac as the full moon. Victims of violence included those patients sustaining blunt assault, gunshot wounds, and stabbings. There was no statistical difference in number of trauma admissions between the full moon, 129 patients per 36 days (mean, 3.58), and nonfull moon days, 1,315 patients per 330 days (mean, 3.98). Mortality rate, 5.4% versus 10.3%; mean Injury Severity Score, 13 versus 15; and mean length of stay, ten versus 12 days, were not significantly different during the full moon and nonfull moon days. Victims of violence were admitted at a similar frequency on full moon, 16 patients per 36 days (mean, 0.444), and nonfull moon days, 183 patients per 330 days (mean, 0.555). We conclude that the belief in the deleterious effects of the full moon on major trauma is statistically unfounded.

Folklore↗
PubMed2004

The full moon and admission to emergency rooms.

OBJECTIVE: The purpose of this study was to investigate an ancient hypothesis; the moon effect might increase incidence of injuries and hence admission of patients with trauma to Emergency Rooms (ERs) on full moon days. METHODS: During thirteen months, 58000 trauma patients admitted in three hospitals that had the highest load of trauma patients in Tehran were studied. Due to lack of complete data, 3543 patients (6.1%) were excluded from the study, leaving 54457 cases for further analysis. We selected lunar calendar for our study, so dates of patients' admissions were converted to lunar months and three day- periods with 15th as middle day were defined as full moon days. RESULTS: In our study the number of trauma patients was not increased during the full moon days against other days of lunar month. Statistical analyses of data didn't exhibit a positive relation between full moon days and increasing of trauma patient admission to ERs. An association between assault and attempted suicide was not observed around the full moon days either. The results did not show significant reduction of GCS score of patients on full moon days and there was not any increase in severity of traumatic injury sustained during full moon days. CONCLUSIONS: It seems necessary to conduct studies regarding the probability of moon effect through on different database, geographic areas and for appropriate periods in order to reach a conclusive result.

Adolescent↗
PubMed1990

Moon illusion in pictures: a multimechanism approach.

The existence of the moon illusion in pictorial representations was demonstrated in 6 experiments. Ss either judged the size of the moon in pictures, depicted as on the horizon or high in the sky, or drew horizon and elevated moons. The horizon moon was consistently judged to be larger than the elevated moon, independent of the angle at which the pictures are viewed. The distance paradox usually observed with the moon illusion (horizon moon apparently closer than the elevated moon) also exists in pictures. The magnitude of both size and distance effects depends on the salience of depicted depth cues. The pattern of results suggests that the moon illusion is caused by several interacting mechanisms and that use of pictorial stimuli may allow the separation of various cognitive from physiological contributions to the illusion.

Attention↗
PubMedDate not supplied

Gravitational effects of the period of high tides and the new moon on lunacy.

In this report, the established timing of terrestrial tidal gravity fluxes is examined to assess the role of the full moon per se in modern gravitational lunacy theory. The results show that the principal tidal gravity fluxes are semidiurnal, with lesser diurnal and even smaller fortnightly components. There are no uniquely monthly components that would correspond to the period of the full moon. This means that the gravitational effects of the new moon are equivalent to those of the full moon. Furthermore, the gravitational effects associated with the times of high tide are even greater than those associated with the moon phases. Using the technique of reductio ad absurdum, I suggest that lunacy effects, if indeed there are any, should occur twice each day (high tides) but should be more pronounced during the new moon and full moon (spring tides). On the basis of this analysis, I would recommend that all studies that have compared hospital records with the full moon be redone to coincide with the proper timing as found in this report.

Atmospheric Pressure↗
PubMed2004

The influence of the full moon on the number of admissions related to gastrointestinal bleeding.

The objective of this study was to analyse whether the number of admissions for gastrointestinal bleeding to our bleeding unit increases during the full moon. In a prospective study, we included 447 consecutive patients with gastrointestinal haemorrhage admitted to our bleeding unit during a period of two years. The number of admissions was allocated to the corresponding day of the lunar cycle, and full moon and non-full moon days were compared. A wide variation in the number of admissions throughout the lunar cycle was observed. There were 26 admissions on the 25 days of full moon and 421 admissions in the remaining 713 days of non-full moon. This difference was mainly related to a higher incidence of haemorrhage in men and variceal haemorrhage at full moon. The results of this study suggest an increase in the number of admissions related to gastrointestinal haemorrhage in our bleeding unit during the full moon, especially in men and in patients experiencing variceal haemorrhage. However, the wide variation in the number of admissions throughout the lunar cycle could limit interpretation of the results. Therefore, further studies are needed to clarify the possible influence of the moon on gastrointestinal haemorrhage.

Adult↗
PubMed2000

Theoretical studies of molybdenum peroxo complexes [MoOn(O2)3-n(OPH3)] as catalysts for olefin epoxidation.

The equilibrium geometries of the molybdenum oxo/peroxo compounds MoOn(O2)3-n and the related complexes [MoOn(O2)3-n(OPH3)] and [MoOn(O2)3-n(OPH3)(H2O)] (n = 0-3) have been calculated using gradient-corrected density-functional theory at the B3LYP level. The structures of the peroxo complexes with ethylene ligands [MoOn(O2)3-n(C2H4)] and [MoOn(O2)3-n(OPH3)(C2H4)] (n = 1, 2) where ethylene is directly bonded to the metal have also been optimized. Calculations of the metal-ligand bond-dissociation energies show that the OPH3 ligand in [MoOn(O2)3-n(OPH3)] is much more strongly bound than the ethylene ligand in [MoOn(O2)3-n(C2H4)]. This makes the substitution of phosphane oxide by olefins in the epoxidation reaction unlikely. An energy-minimum structure is found for [MoO(O2)2(OPH3)(C2H4)], for which the dissociation of C2H4 is exothermic with D0 = -5.2 kcal/mol. The reaction energies for the perhydrolysis of the oxo complexes with H2O2 and the epoxidation of ethylene by the peroxo complexes have also been calculated. The peculiar stability of the diperoxo complex [MoO(O2)2(OPH3)(H2O)] can be explained with the reaction energies for the perhydrolysis of [MoOn(O2)3-n(OPH3)(H2O)]. The first perhydrolysis step yielding the monoperoxo complex is less exothermic than the second perhydrolysis reaction, but the further reaction with H2O2 yielding the unknown triperoxo complex is clearly endothermic. CDA analysis of the metal-ethylene bond shows that the binding interactions are mainly caused by charge donation from the ligand to the metal.

Journal Article↗
PubMed2001

Origin of the Moon in a giant impact near the end of the Earth's formation.

The Moon is generally believed to have formed from debris ejected by a large off-centre collision with the early Earth. The impact orientation and size are constrained by the angular momentum contained in both the Earth's spin and the Moon's orbit, a quantity that has been nearly conserved over the past 4.5 billion years. Simulations of potential moon-forming impacts now achieve resolutions sufficient to study the production of bound debris. However, identifying impacts capable of yielding the Earth-Moon system has proved difficult. Previous works found that forming the Moon with an appropriate impact angular momentum required the impact to occur when the Earth was only about half formed, a more restrictive and problematic model than that originally envisaged. Here we report a class of impacts that yield an iron-poor Moon, as well as the current masses and angular momentum of the Earth-Moon system. This class of impacts involves a smaller-and thus more likely-object than previously considered viable, and suggests that the Moon formed near the very end of Earth's accumulation.

Journal Article↗
PubMed2005

Moon orientation in adult and young sandhoppers under artificial light.

Our experiments, carried out at night and during the day on adults and laboratory-born young of the sandhopper Talitrus saltator, deal with the identification and use of the moon as an orientating factor. Sandhoppers were released in an apparatus (a Plexiglas dome) that produced a scenario similar to the natural one (with artificial sky, moon or sun illuminated at different intensities). When tested at night, the adult and young sandhoppers used the artificial moon like the natural one, independently of the intensity of illumination of the artificial sky and moon. In other words, sandhoppers tested at night always identified the artificial moon as the moon and never as the sun. In daytime releases, the seaward orientation failed at low intensities of artificial sky and sun illumination (3.07 and 1.55 microW cm2, respectively), whereas the sun compass was used effectively at higher levels of artificial sun and sky illumination. The innate ability of moon compass orientation in inexpert young sandhoppers was demonstrated even under artificial light.

Age Factors↗
PubMed2005

Nanophotonic crescent moon structures with sharp edge for ultrasensitive biomolecular detection by local electromagnetic field enhancement effect.

We present novel gold nanophotonic crescent moon structures with a sub-10 nm sharp edge, which can enhance local electromagnetic field at the edge area. The formation of unconventional nanophotonic crescent moon structure is accomplished by using a sacrificial nanosphere template and conventional thin film deposition method, which allows an effective batch nanofabrication and precise controls of nanostructure shapes. Unique multiple scattering peaks are observed in a single gold nanocrescent moon with dark-field white light illumination. A 785 nm near-infrared (NIR) diode laser was used as the excitation source to induce the amplified scattering field on the sharp edge of the single gold nanocrescent moon. The Raman scattering spectrum of Rhodamine 6G molecules adsorbed on the single gold nanocrescent moon are characterized, and the Raman enhancement factor of single gold nanocrescent moon is estimated larger than 10(10), which suggests the potential applications of gold nanocrescent moons in ultrasensitive biomolecular detection and cellular imaging using surface enhanced Raman spectroscopy.

Electromagnetic Fields↗
PubMed2003

Chaos-assisted capture of irregular moons.

It has been thought that the capture of irregular moons--with non-circular orbits--by giant planets occurs by a process in which they are first temporarily trapped by gravity inside the planet's Hill sphere (the region where planetary gravity dominates over solar tides). The capture of the moons is then made permanent by dissipative energy loss (for example, gas drag) or planetary growth. But the observed distributions of orbital inclinations, which now include numerous newly discovered moons, cannot be explained using current models. Here we show that irregular satellites are captured in a thin spatial region where orbits are chaotic, and that the resulting orbit is either prograde or retrograde depending on the initial energy. Dissipation then switches these long-lived chaotic orbits into nearby regular (non-chaotic) zones from which escape is impossible. The chaotic layer therefore dictates the final inclinations of the captured moons. We confirm this with three-dimensional Monte Carlo simulations that include nebular drag, and find good agreement with the observed inclination distributions of irregular moons at Jupiter and Saturn. In particular, Saturn has more prograde irregular moons than Jupiter, which we can explain as a result of the chaotic prograde progenitors being more efficiently swept away from Jupiter by its galilean moons.

Journal Article↗
PubMedDate not supplied

Full moon and crime.

The incidence of crimes reported to three police stations in different towns (one rural, one urban, one industrial) was studied to see if it varied with the day of the lunar cycle. The period of the study covered 1978-82. The incidence of crimes committed on full moon days was much higher than on all other days, new moon days, and seventh days after the full moon and new moon. A small peak in the incidence of crimes was observed on new moon days, but this was not significant when compared with crimes committed on other days. The incidence of crimes on equinox and solstice days did not differ significantly from those on other days, suggesting that the sun probably does not influence the incidence of crime. The increased incidence of crimes on full moon days may be due to "human tidal waves" caused by the gravitational pull of the moon.

Crime↗