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1.
Chinese and Japanese historical records of daytime fireballs, and world-wide daytime meteorite falls in the catalogue have been investigated. Among them, there are 253 and 104 records of great daytime fireballs in China and in Japan respectively, and 506 meteorite falls in the daytime are recorded in the Catalogue of Meteorites (1985).The same trends of seasonal and daily variations in the flux of daytime fireballs are clearly seen in both Chinese and Japanese records, and then the distributions of the daytime fireballs seem to suggest the association with meteorites and near-earth minor planets rather than with comets.Possible relations with minor planets, such as (1566) Icarus, (3671) Dionysius, (4450) Pan, (4486) Mithra and others are suggested.  相似文献   

2.
Numbers of meteors recorded in Chinese and Japanese histories are counted. Two distinct maxima in Chinese records are found in the 11th and 15th centuries, and the latter is also recorded in Japan. Of those records, numbers of bright meteors with sound and great fireballs that appeared in the daytime are also investigated.Correlations between the meteor numbers and the apparitions of naked-eye comet likely to be found, and seasonal variations in the meteor flux recorded during nineteen centuries show two maxima in July–August and October–November, the latter may be related to the Taurid complex.  相似文献   

3.
A power spectrum analysis is applied to the yearly statistics of Chinese historical records of fireballs. The results show that sound is an important indicator of origin. Noisy fireballs have the following possible periods in years: 170.6 ± 0.0, 102.4 ± 0.0, 66.1 ± 2.2, 27.3 ± 0.4, 23.3 ± 0.0, 17.9 ± 0.4, 14.8 ± 0.1, 12.4 ± 0.1, 10.5 ± 0.3. Noisy fireballs and meteorite falls have basically the same periods, and both originate in the asteroid belt. We think that the factors affecting both are the Yarkovsky effect and the perturbations by Jupitor. The 10.5-yr, 23.3-yr and 66.1-yr periods are related to the Yarkovsky effect and the 12.4-yr, 17.9-yr, 102.4-yr and 170.6-yr periods, to Jovian perturbations. The 14.8-yr and 27.3-yr periods may be due to the combined effect of the two, or to some other causes.  相似文献   

4.
Abstract— Statistics of witnessed and recovered meteorite falls found in Chinese historical texts for the period from 700 B.C. to A.D. 1920 are presented. Several notable features can be seen in the binned distribution as a function of time. An apparent decrease in the number of meteorite reports in the 18th century is observed. An excess of observed meteorite falls in the period from 1840 to 1880 seems to correspond to a similar excess in European data. A x2 probability test suggests that the association between the two data sets are real. Records of human casualties and structural damage resulting from meteorite falls are also given. A calculation based on the number of casualty events in the Chinese meteorite records suggests that the probability of a meteorite striking a human is far greater than previous estimates. However, it is difficult to verify the accuracy of the reported casualty events.  相似文献   

5.
Plausible meteorite mass distributions imply that in the Prairie Network data there must be many fainter fireballs produced by meteorites with physical properties that, except for mass, are very similar to the recovered ordinary chondrite (H5) Lost City. Four criteria are proposed for identifying these other meteorites among the fireballs. These are: deceleration to final velocity ≤8 km/sec; a photometric mass/dynamic mass ratio within a factor of 2 of that of Lost City, agreement of the observed and theoretical single body end heights (calculated using dynamic mass), and a lightcurve no more irregular than those of the three recovered fireballs. These criteria can be related to the PE criterion of Ceplecha and McCrosky, but include a wider range of observational data, and also differ from the PE criterion in avoiding inclusion of data not helpful to the particular problem of identifying ordinary chondrite fireballs. By use of our criteria, 27 Prairie Network fireballs are identified as being meteorites comparable to or greater in strength and density to Lost City, most of these should be ordinary chondrites. The orbital element distributions of these objects span a wide range, include those of recovered fireballs, and show that the 4.0-AU aphelion of the Pribram meteorite is not unusually large. Perihelia are concentrated near 1.0 AU, in agreement with previous inferences from time-of-fall and radiant distributions, demonstrating the usefulness of these data based on visual observations.  相似文献   

6.
We propose that the Taurid meteor shower may contain bodies able to survive and be recovered as meteorites. We review the expected properties of meteorite‐producing fireballs, and suggest that end heights below 35 km and terminal speeds below 10 km s?1 are necessary conditions for fireballs expected to produce meteorites. Applying the meteoroid strength index (PE criteria) of Ceplecha and McCrosky (1976) to a suite of 33 photographically recorded Taurid fireballs, we find a large spread in the apparent meteoroid strengths within the stream, including some very strong meteoroids. We also examine in detail the flight behavior of a Taurid fireball (SOMN 101031) and show that it has the potential to be a (small) meteorite‐producing event. Similarly, photographic observations of a bright, potential Taurid fireball recorded in November of 1995 in Spain show that it also had meteorite‐producing characteristics, despite a very high entry velocity (33 km s?1). Finally, we note that the recent Maribo meteorite fall may have had a very high entry velocity (28 km s?1), further suggesting that survival of meteorites at Taurid‐like velocities is possible. Application of a numerical entry model also shows plausible survival of meteorites at Taurid‐like velocities, provided the initial meteoroids are fairly strong and large, both of which are characteristics found in the Taurid stream.  相似文献   

7.
Abstract— We explore the orbital dynamics of Earth‐crossing objects with the intent to understand the time scales under which an “orbital stream” of material could produce time‐correlated meteorite falls. These “meteoroid streams” have been suggested to be associated with three well‐known meteorite‐dropping fireballs (Innisfree, Peekskill, and P?íbram). We have performed two different analyses of the statistical significance of the “orbital similarity,” in particular calculating how often orbits of the same level of similarity would come from a random sample. Secondly, we have performed extremely detailed numerical integrations related to these three cases, and we find that if they were streams of objects in similar orbits, then they would become “decoherent” (in the sense that the day‐of‐fall of meteorites of these streams become almost random) on time scales of 104–105 yr. Thus, an extremely recent breakup would be required, much more recent that the cosmic ray exposure ages of the recovered falls in each case. We conclude that orbital destruction is too efficient to allow the existence of long‐lived meteoroid streams and that the statistical evidence for such streams is insufficient; random fall patterns show comparable levels of clustering.  相似文献   

8.
Abstract— Terminal bursts and fragmentations of meteoritic fireballs in the atmosphere may now be accurately located in four dimensions (three spatial + temporal) using seismic arrival times of their acoustic waves recorded by seismometer, camera, microphone, and/or infrasound stations on the ground. A computer program, SUPRACENTER, calculates travel times by ray tracing through realistic atmospheres (that include winds) and locates source positions by minimization of travel time residuals. This is analogous to earthquake hypocenter location in the solid Earth but is done through a variably moving medium. Inclusion of realistic atmospheric ray tracing has removed the need for the simplifying assumption of an isotropic atmosphere or an approximation to account for “wind drift.” This “drift” is on the order of several km when strong, unidirectional winds are present in the atmosphere at the time of a fireball's occurrence. SUPRACENTER‐derived locations of three seismically recorded fireballs: 1) the October 9, 1997 El Paso superbolide; 2) the January 25, 1989 Mt. Adams fireball; and 3) the May 6, 2000 Morávka fireball (with its associated meteorite fall), are consistent with (and, probably, an improvement upon) the locations derived from eyewitness, photographic, and video observations from the respective individual events. If direct acoustic seismic arrivals can be quickly identified for a fireball event, terminal burst locations (and, potentially, trajectory geometry and velocity information) can be quickly derived, aiding any meteorite recovery efforts during the early days after the fall. Potentially, seismic records may yield enough trajectory information to assist in the derivation of orbits for entering projectiles.  相似文献   

9.
Similarities among impact structures on different planets and satellites suggest that the cratering process transcends variations in both target and impactor. In particular, impact may control the spacing of concentric rings, if not their actual emplacement. In at least four respects the scaled horizontal dimensions of complex meteorite-impact structures on Earth resemble those of multi-ring basins and large craters on the Moon, Mars, Mercury, and some outer satellites: (1) Base diameter of the (topographic) central peak is a constant 20% to 25% of the rim diameter in small complex craters; (2) it averages only half as much in large structures that also have concentric rings; (3) the inner ring of a two-ring crater lacking a central peak is half the diameter of the outer ring; (4) adjacent rings of complex craters that have more than two concentric rings are spaced at a constant interval of about (2.0 ± 0.2)0.5 D, both inside and outside the main ring. Two minor differences in morphology suggest that uniquely terrestrial conditions may control some horizontal dimensions of meteorite craters: (1) the inner ring of a two-ringed structure that also has a central peak is 0.5X the diameter of the outer, not 0.4X as it is for peak-plus-ring basins on the planets; and (2) two-ring and multi-ring meteorite craters occupy the same size range, whereas on planets most two-ring basins are smaller than multi-ring basins.  相似文献   

10.
Abstract— We derive values for the number and size distributions of meteorites landing on Earth from a study of photographic observations of bright fireballs with the Canadian camera network. The observations cover 11 years from 1974 to 1985. This analysis is an extension of a previous study and represents a 30% increase in the data base. The cumulative plot of numbers vs estimated mass of the largest fragment for each event shows a change in slope near 0.6 kg due to a deficiency of small meteorites surviving from the group of slow fireballs. The change can be explained by a mass dependence of the fraction of the incoming object that survives as the largest fragment. For larger falls, the main mass appears to represent a decreasing fraction of the total mass of the surviving meteorites and estimates of these effects are used to derive the final distribution of both main masses and total masses of meteoritic events. For total masses greater than 1 kg the population index is 1.82, close to previous estimates. About 9 events per year drop at least 1 kg of meteorites in an area of a million square km and the same area receives an annual influx of 54 kg from meteorite events with total masses between 0.01 and 100 kg. There is sufficient confidence in these results that they may be used for comparison of the present flux of meteorites with values inferred for other times, in particular the long accumulation times of the Antarctic meteorite collections.  相似文献   

11.
To date, several meteorites have been found for which their flight in the atmosphere was recorded by special fireball camera networks. Because of this, a thorough analysis of the instrumentally registered falls is of current importance. For such fireballs, not only the high-quality photo images of the motion in the atmosphere exist, but also the density and the shape of the meteor body fragments reached the Earth’s surface are known for sure. In the present study, for the Innisfree, Lost City, and Pribram fireballs, new models of the entry to the atmosphere have been built. The values of the ballistic coefficient and the mass-loss parameter providing the best approximation for the observations of the luminous trajectory segment with the analytical solution of the meteor physics equations have been obtained. From recent results of the numerical experiments on the supersonic airflow of bodies of various shapes, the preatmospheric masses of the fireballs, as well as the dynamic estimates of the mass at the other trajectory points, were obtained. In particular, the terminal mass of the fireballs in the lower segment of the analyzed trajectories is in good agreement with the total mass of the meteorite material recovered in all of the cases considered. Moreover, to calculate the acceleration of the meteor bodies, a new analytical formula has been suggested, which allows the obtained theoretical time dependencies of the velocity and altitude to be compared with the observational data.  相似文献   

12.
Sixty fireball cameras operated in Western Canada from 1971 to 1985. Over one thousand (1016) fireballs were recorded at more than one station, but only 367 were reduced, of which 285 have been published, including that of the Innisfree meteorite. Digitization of all the data is underway, and procedures are being developed which will allow the automatic reduction of events not previously examined. The results of the analysis of 80 fireballs reduced but not previously published are presented. When the new analysis is complete, the MORP archive will be a valuable source of information on meteoroid orbits.  相似文献   

13.
Minor bodies that, at the present stage, have orbital characteristics similar to those of the Pribram meteorite and that differ from it in the date of activity of the radiants by no more than a 1.2-month period in either direction were detected on the basis of catalog data on the orbits of asteroids, individual fireballs, and fireball and meteor streams obtained from photographic observations. The following objects comprising the Prbram family are among such minor bodies: three asteroids (1863, 4486, and J98S70J) of the Apollo group, three fireball streams, five meteor streams, and ten fireballs. This extensive system of bodies consists of three branches: a Northern (N), an Ecliptical (Q), and a Southern (S) Branch. The family of meteor streams associated with the periodic comet Pons–Winnecke appears to be related to this family. Thus, there emerges an intricate complex of small bodies that is similar to the well-known Taurid complex. In the distribution of various populations of minor bodies according to the quantity c of the Tisserand criterion, both of these complexes of minor bodies, like the group of cometoids (or cometlike asteroids), are situated in the region of unstable motion or, to be more exact, near the gap that arises in the L 2 and L 3 collinear points of libration.  相似文献   

14.
Hong-Jin Yang  Changbom Park 《Icarus》2005,175(1):215-225
We have compiled and analyzed historical Korean meteor and meteor shower records in three Korean official history books, Samguksagi which covers the three Kingdoms period (57 B.C.-A.D. 935), Goryeosa of Goryeo dynasty (A.D. 918-1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392-1910). We have found 3861 meteor and 31 meteor shower records. We have confirmed the peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids, or Leonids through the Monte Carlo test. The peaks persist from the period of Goryeo dynasty to that of Joseon dynasty, for almost one thousand years. Korean records show a decrease of Perseids activity and an increase of Orionids/north-Taurids/Leonids activity. We have also analyzed seasonal variation of sporadic meteors from Korean records. We confirm the seasonal variation of sporadic meteors from the records of Joseon dynasty with the maximum number of events being roughly 1.7 times the minimum. The Korean records are compared with Chinese and Japanese records for the same periods. Major features in Chinese meteor shower records are quite consistent with those of Korean records, particularly for the last millennium. Japanese records also show Perseids feature and Orionids/north-Taurids/Leonids feature, although they are less prominent compared to those of Korean or Chinese records.  相似文献   

15.
中国古代火流星记录的统计分析   总被引：1，自引：0，他引：1  
本文对中国古代火流星记录,按年统计,用功率谱这一数学方法对它们进行分析。结果发现声音是衡量火流星起源的一个重要参数。有声音的火流星具有170.6±0.0,102.4±0.0,66.1±2.2,27.3±0.4,23.3±0.0,17.9±0.4,14.8±0.1,12.4±0.1,10.5±0.3年的可能周期。有声火流星与陨石坠落周期基本相同,是与陨石同源的,来自小行星带。我们认为影响有声火流星和陨石下落的因素是太阳辐射引起的Yarkovsky效应和木星摄动。有声火流星的10.5±0.3,23.2±0.0,66.1±2.2年周期与Yarkovsky效应有关。12.4±0.1,17.9±0.4,102.4±0.0,170.6±0.0周期与木星摄动有关。至于14.8±0.1,27.3±0.4的周期,可能是木星摄动与Yarkovsky效应联合作用或其他原因所致。  相似文献   

16.
Abstract— The polycyclic aromatic hydrocarbon (PAH) anthracene was oxidized by exposure to ultraviolet (UV) radiation in H2O ice under simulated astrophysical conditions, forming several anthracene ketones (9‐anthrone, 1,4‐anthraquinone, and 9,10‐anthraquinone) and alcohols (1‐anthrol and 2‐anthrol). Two of the ketones produced have been detected in the Murchison meteorite but, to our knowledge, there has been no search for the alcohols or other oxidized anthracenes in meteorites. These results seem consistent with the possibility that interstellar ice photochemistry could have influenced the inventory of aromatics in meteorites. Since quinones are also fundamental to biochemistry, their formation in space and delivery to planets is relevant to studies relating to the habitability of planets and the evolution of life.  相似文献   

17.
Meteorite camera networks have provided reliable data on typical orbits for meteorites. Using an adopted distribution of 20 orbits we determine the relative rates of meteorite falls over the surface of the earth taking account of the important effects due to the earth's gravity. The data are then used to study the expected variation in rates as a function of daylight, twilight or night conditions; time of day; season of the year; and geographic latitude. The rates of meteorite falls have a deep minimum near the area of the earth facing the earth's apex but a surprisingly broad maximum on the opposite side, facing the antapex. Twilight rates are lower than average and nighttime rates 3% higher than daytime rates. Minimum rates occur near 6h local time and there is a broad maximum from noon to midnight. Rates are highest near the beginning of spring for either hemisphere and lowest near the beginning of autumn. The decline in rates with increasing latitude is quite moderate. The existing camera networks observe average fall rates at night which are very close to the average rate over the whole earth for the whole year.  相似文献   

18.
Abstract— Recent estimates of the current rate of meteorite falls have been derived from camera network observations and from the statistics of the recovery of small fragments in Roosevelt County, New Mexico. The results are discordant. The integrated sky coverage for the camera data is an order of magnitude greater than the long exposure over small areas in New Mexico, yet the number of inferred events is comparable. We examine potential problems and find no effects other than random ones to bias the camera data. New data on the total number of suitable fireballs indicate that the flux from the camera network is already close to the upper limit imposed by the count of over 700 fireballs. By contrast, the calibration of the decay time for small fragments in New Mexico appears insecure and could account for a factor-of-three discrepancy. The large area of a typical strewn field relative to the small search areas is also a serious problem that remains uncalibrated. There are problems with the application of either the camera results or the New Mexico data to the statistics of recoveries in Antarctica since the Antarctic search areas are not free from the strewn-field problem. Since there is no evidence for a substantial change in the infall rate in intervals less than the ages of the collecting surfaces, we believe the camera network flux data remain the best estimate for the arrival rate of small meteorites on Earth.  相似文献   

19.
Meteorites are delivered from the asteroid belt by way of chaotic zones (Wisdom 1985a). The dominant sources are believed to be the chaotic zones associated with the ν6 secular resonance, the 3:1 mean motion resonance, and the 5:2 mean motion resonance. Though the meteorite transport process has been previously studied, those studies have limitations. Here I reassess the meteorite transport process with fewer limitations. Prior studies have not been able to reproduce the afternoon excess (the fact that approximately twice as many meteorites fall in the afternoon as in the morning) and suggested that the afternoon excess is an observational artifact; here it is shown that the afternoon excess is in fact consistent with the transport of meteorites by way of chaotic zones in the asteroid belt. By studying models with and without the inner planets it is found that the inner planets significantly speed up the transport of meteorites.  相似文献   

20.
The comparison of the Tunguska body explosion with the effect of terminal flares of meteors and fireballs leads us to the conclusion that these events are of a similar nature but differ only by their scale. We consider that the dynamics of progressive breaking and evaporation of meteoric bodies during their entry into the terrestrial atmosphere could explain the terminal burst. An extremely porous body model for the Tunguska meteorite was analysed and rejected as unsatisfactory. The realistic values of the initial velocity (～30 km/sec) and of the inclination angle for the Tunguska's trajectory (5–15°) give orbital elements not in contradiction with the cometary origin of the Tunguska body.  相似文献   

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