Search

Our planet experiences falls of meteorites with different airburst and ground impact risk. Some of these meteors can survive after the atmospheric passage and fall into the ground. Although there are claims that people were hit and killed by meteorites in history, the historical records do not prove this fact so far. This issue might be due to the fact that either the manuscript was written in a language other than English or there is not enough interest in historical records. To the best of our knowledge, we show the first proof of an event ever that a meteorite hit and killed a man and left paralyzed another on August 22, 1888 in Sulaymaniyah, Iraq, based on three manuscripts written in Ottoman Turkish that were extracted from the General Directorate of State Archives of the Presidency of the Republic of Turkey. This event was also reported to Abdul Hamid II (34th sultan of the Ottoman Empire) by the governor of Sulaymaniyah. These findings suggest other historical records may still exist that describe other events that caused death and injuries by meteorites. [ABSTRACT FROM AUTHOR]

Orbital elements are presented for 70 of the 95 meteor showers considered “established” by the International Astronomical Union. From 2010 October 21 until 2013 March 31, the low-light-video based Cameras for Allsky Meteor Surveillance project (CAMS) measured a total of 110,367 meteoroid trajectories and pre-atmospheric orbits from mostly −2 to +4 magnitude meteors with a precision of <2° (median 0.4°) in apparent radiant direction and <10% (median 0.9%) in speed. This paper discusses how the already established showers manifest in this data. Newly resolved components in the radiant distribution shed light on the dynamics and physical lifetime of parent bodies and their meteoroids. Many multi-component showers have associated parent bodies with nodal lines not much rotated from that of their meteoroids (Encke Complex, Machholz Complex, Phaethon Complex, and now also the 169P/NEAT Complex). These may result from a parent body disruption cascade, with the disruption-generated meteoroids fading on the short timescale of a few hundred to a few thousand years. In particular, the Northern and Southern Taurids of the Encke Complex are decomposed here into 19 individual streams. Seven of these streams can be paired with mostly sub-km sized potential parent body asteroids that move in 2P/Encke-like orbits that span the narrow semi-major axis range of 2.20–2.35 AU. The meteoroids in these Taurid streams do not survive long enough for the nodal line to fully rotate relative to that of their parent body. [ABSTRACT FROM AUTHOR]

Leading up to the 2015 IAU General Assembly, the International Astronomical Union’s Working List of Meteor Showers included 486 unconfirmed showers, showers that are not certain to exist. If confirmed, each shower would provide a record of past comet or asteroid activity. Now, we report that 41 of these are detected in the Cameras for Allsky Meteor Surveillance (CAMS) video-based meteor shower survey. They manifest as meteoroids arriving at Earth from a similar direction and orbit, after removing the daily radiant drift due to Earth’s motion around the Sun. These showers do exist and, therefore, can be moved to the IAU List of Established Meteor Showers. This adds to 31 previously confirmed showers from CAMS data. For each shower, finding charts are presented based on 230,000 meteors observed up to March of 2015, calculated by re-projecting the drift-corrected Sun-centered ecliptic coordinates into more familiar equatorial coordinates. Showers that are not detected, but should have, and duplicate showers that project to the same Sun-centered ecliptic coordinates, are recommended for removal from the Working List. [ABSTRACT FROM AUTHOR]

The Cameras for Allsky Meteor Surveillance (CAMS) video-based meteoroid orbit survey adds 60 newly identified showers to the IAU Working List of Meteor Showers (numbers 427, 445–446, 506–507, and part of 643–750). 28 of these are also detected in the independent SonotaCo survey. In total, 230 meteor showers and shower components are identified in CAMS data, 177 of which are detected in at least two independent surveys. From the power-law size frequency distribution of detected showers, we extrapolate that 36% of all CAMS-observed meteors originated from ∼700 showers above the N = 1 per 110,000 shower limit. 71% of mass falling to Earth from streams arrives on Jupiter-family type orbits. The transient Geminids account for another 15%. All meteoroids not assigned to streams form a sporadic background with highest detected numbers from the apex source, but with 98% of mass falling in from the antihelion source. Even at large ∼7-mm sizes, a Poynting–Robertson drag evolved population is detected, which implies that the Grün et al. collisional lifetimes at these sizes are underestimated by about a factor of 10. While these large grains survive collisions, many fade on a 10 4 -y timescale, possibly because they disintegrate into smaller particles by processes other than collisions, leaving a more resilient population to evolve. The meteors assigned to the various showers are identified in the CAMS Meteoroid Orbit Database 2.0 submitted to the IAU Meteor Data Center, and can be accessed also at http://cams.seti.org . [ABSTRACT FROM AUTHOR]

Abstract: First results are presented from a newly developed meteoroid orbit survey, called CAMS – Cameras for Allsky Meteor Surveillance, which combines meteor detection algorithms for low-light video observations with traditional video surveillance tools. Sixty video cameras at three stations monitor the sky above 31° elevation. Goal of CAMS is to verify meteor showers in search of their parent comets among newly discovered near-Earth objects. This paper outlines the concept of operations, the hardware, and software methods used during operation and in the data reduction pipeline, and accompanies the data release of the first batch of meteoroid orbits. During the month of November 2010, 2169 precisely reduced meteoroid trajectories from 17 nights have an error in the apparent radiant of the trajectory <2° and error in speed <10%. Median values of the error are 0.31° and 0.53km/s, respectively, sufficient to resolve the intrinsic dispersion of annual meteor showers and resolve minor showers from the sporadic background. The limiting visual magnitude of the cameras is +5.4, recording meteors of +4 magnitude and brighter, bright enough to stand out from the mostly fainter sporadic meteors detected as under dense radar echoes. CAMS readily detected all established showers (6) active during the clear nights in November. Of the showers that needed confirmation, we confirm the theta Aurigids (THA, IAU#390), the chi Taurids (CTA, IAU#388), and the omicron Eridanids (OER, IAU#338). We conclude that the iota November Aurigids (IAR, IAU#248) are in fact the combined activity of the theta Aurigids and chi Taurids, and this shower should be dismissed from the list. Finally, there is also a clustering consistent with the zeta Cancrids (ZCN, IAU#243), but we cannot exclude that this is lower perihelion dust belonging to the Orionid shower. Data are submitted to the IAU Meteor Data Center on a semi-regular basis, and can be accessed also at http://cams.seti.org. [Copyright &y& Elsevier]

Abstract: In 2006, Earth encountered a trail of dust left by Comet 55P/Tempel-Tuttle two revolutions ago, in A.D. 1932. The resulting Leonid shower outburst was observed by low light level cameras from locations in Spain. The outburst peaked on 2006 Nov. 19d 04h39m ± 3m UT (predicted: 19d 04h50m ± 15m UT), with a FWHM of 43 ± 10 min (predicted: 38 min), at a peak rate of (predicted: 50–200 per hour). A low level background of older and brighter Filament Leonids () was also present, which dominated rates for Leonids brighter than magnitude +4. The 1932-dust outburst was detected among Leonids of +0 magnitude and brighter. These outburst Leonids were much brighter than expected, with a magnitude distribution index (predicted: and up). Trajectories and orbits of 24 meteors were calculated, most of which are part of the Filament component. Those that were identified as 1932-dust grains penetrated just as deep as Leonids in past encounters. We conclude that larger meteoroids than expected were present in the tail of the 1932-dust trail and meteoroids did not end up there because of low density. We also find that the radiant position of meteors in the Filament component scatter in a circle with radius 0.39°, which is wider than in 1998, when the diameter was 0.09°. This supports the hypothesis that the Filament component consists of meteoroids in mean-motion resonances. [Copyright &y& Elsevier]

On November 18, 2001, the Earth crossed more than one dust trail of comet 55P/Tempel-Tuttle, with meteoroid stream centers located just inside and outside of Earth’s orbit. The relative flux intensity of the resulting meteor storm peaks can be used as a sensitive measure of the relative position of the dust trails. Unfortunately, the precise value of the magnitude distribution index plays a large role in how both storms were perceived by different video cameras. That is, the different observing conditions of each instrument require making corrections to the relative flux. Through the analysis of video observations of both airborne and ground-based observations and the use of a meteor simulation tool, we attempt to estimate the magnitude distribution index and the relative peak intensity of the Leonid meteor storms from 2001. This in turn is used to provide insight into the predictive capabilities of the various dust trail models. [Copyright &y& Elsevier]

The recent intense Leonid meteor storms have seen a rejuvenation of optical meteor studies, including the first application of cooled CCD technologies and the first large-scale use of intensified slit-less video spectrographs. The Leonid Multi-Instrument Aircraft Campaign has provided a wealth of diverse new data. This paper is an initial attempt to ask what the myriad of Leonid observations have taught us, by bringing the observations and early modeling efforts together, and by presenting a `grand vision'' of the interaction of fast meteoroids with the atmosphere. An overview is given of the physical conditions in meteors, their products, and their influence on the Earth''s atmosphere. [Copyright &y& Elsevier]

Long-period comets have narrow one-revolution old dust trails that can cause meteor outbursts when encountered by Earth. To facilitate observing campaigns that will characterize and perhaps help find Earth-threatening, long-period comets from their trace of meteoric debris, we use past accounts of outbursts from 14 different showers to calculate the future dust trail positions near Earth’s orbit. We also examine known near-Earth, long-period comets and identify five potential new showers, which can be utilized to learn more about these objects. We demonstrate that it is the one-revolution trail that is responsible for meteor outbursts. A method that calculates in what year these showers are likely to return and at what hour is presented. The calculations improve on earlier approximate methods that used the Sun’s reflex motion to gauge the trail motion relative to Earth’s orbit. [Copyright &y& Elsevier]

We report here evidence for significant transverse spread of the light production region in bright Leonid meteors. One Leonid meteor has an apparent spread in the light production region of about 600 m perpendicular to the flight path for the meteor, that transverse spread persisting for at least 0.3 s. We have also detected short-duration, jet-like features emanating from a bright Leonid meteor recorded in 1998. These jet-like features have maximum spatial dimensions up to 1.9 km. While we cannot definitively rule out instrumental artefacts as a cause for these jet-like features, they may be evidence of motion contributing to the observed spatial spread in the light production region. [ABSTRACT FROM AUTHOR]

The CAMS New Zealand meteor shower survey detected a brief outburst of delta Pavonids (IAU shower 120, code DPA) with a compact radiant on March 31, 2019. This is the first instrumental detection of a shower long suspected to exist by visual observers monitoring the theoretical radiant of parent comet C/1907 G 1 (Grigg-Mellish), despite it being listed in comet catalogs only with a parabolic orbit. The 2019 detection of an associated meteor shower confirms that this comet moves in an elliptical orbit. The range of allowed orbit solutions fitted to the 1907 observations of the comet strongly correlate node and semi-major axis. Taking into account the difference in node between comet orbit and dust trail, the time of the outburst constrains the comet orbital period to 447 ​± ​80 years (heliocentric), having last been near the sun in A. D. 1460 ​± ​80 years. The corresponding elliptical orbital elements for C/1907 G 1 are presented. The short 23-min duration of the outburst (FWHM ​= ​16 ​min) confirms that C/1907 G 1 is a small comet, having ejected dust with low ejection speeds. It passed close enough to Earth orbit to be a potentially hazardous comet in future returns. • An outburst of meteors on March 31, 2019, shows that parent comet Grigg-Mellish moves in an elliptical orbit and was near the Sun before. • The timing of the outburst, combined with the observations of the comet in 1907, constrains the comet orbital period. • The timing of the outburst, combined with the observations of the comet in 1907, constrains the comet orbital period. • The comet ejected the meteoroids when it was near the Sun in A. D. 1460 ± 80 y. • Because the comet will return, and has a small miss-distance, it is a potential impact hazard to Earth. [ABSTRACT FROM AUTHOR]

The world's meteorite collections contain a very rich picture of what the early Solar System would have been made of, however the lack of spatial context with respect to their parent population for these samples is an issue. The asteroid population is equally as rich in surface mineralogies, and mapping these two populations (meteorites and asteroids) together is a major challenge for planetary science. Directly probing asteroids achieves this at a high cost. Observing meteorite falls and calculating their pre-atmospheric orbit on the other hand, is a cheaper way to approach the problem. The Global Fireball Observatory (GFO) collaboration was established in 2017 and brings together multiple institutions (from Australia, USA, Canada, Morocco, Saudi Arabia, the UK, and Argentina) to maximise the area for fireball observation time and therefore meteorite recoveries. The members have a choice to operate independently, but they can also choose to work in a fully collaborative manner with other GFO partners. This efficient approach leverages the experience gained from the Desert Fireball Network (DFN) pathfinder project in Australia. The state-of-the art technology (DFN camera systems and data reduction) and experience of the support teams is shared between all partners, freeing up time for science investigations and meteorite searching. With all networks combined together, the GFO collaboration already covers 0.6% of the Earth's surface for meteorite recovery as of mid-2019, and aims to reach 2% in the early 2020s. We estimate that after 5 years of operation, the GFO will have observed a fireball from virtually every meteorite type. This combined effort will bring new, fresh, extra-terrestrial material to the labs, yielding new insights about the formation of the Solar System. • A large international collaboration is being set up to observe meteorite falls on Earth, aiming 2% Earth coverage. • The recovery of different types of fresh meteorites helps understanding the early Solar System. • The orbital origins of meteorites also inform us about the hazard posed by larger Near-Earth Objects. [ABSTRACT FROM AUTHOR]