Lably
Skip to content

Meteorite fall

Collected meteorite whose fall was observed

  • 19 min read
  • 6 chapters

Related on Lably

Through Outer space, Asteroid and Tonne

However not all recovered meteorite falls are immediately entered as official meteorites in the MetBull-Database. For a new meteorite to receive an official name, a submission to the Nomenclature Committee must document the location and circumstances of the fall or find, the total known mass, an authoritative scientific classification, and the location of the main mass. In addition, a type specimen must be placed in the permanent custody of an approved institutional repository. The proposed name and documentation are then reviewed and approved by the Nomenclature Committee.

In several cases, recovered material has been described in peer-reviewed publications or studied by universities, museums or established fireball networks, while an official name or classification by the Meteoritical Society is still pending. Some such cases have remained unofficial for many years. Examples include the 2015 San Carlos fall in Uruguay, which was classified as an LL6 chondritic breccia in a peer-reviewed study, and several instrumentally observed falls such as Benghazi Dam, Crawford Bay, Ådalen and Kybo-Lintos, which have subsequently been used in scientific studies of meteorite trajectories and orbits. More recent recoveries remain under study or await formal approval of their names and classifications.

Significance

  • In the most energetic of events, falls are observed by many human observers, and can co-occur with dramatic consequences as seen during the Chelyabinsk meteor event, in which 1,491 people were injured seriously enough to seek medical treatment (most injured from broken glass from the shockwave; no fatalities).
  • Material from observed falls has not been subjected to terrestrial weathering, making the fall an ideal candidate for scientific study into the dynamics of dust and small-body formation and understanding the history of solar system formation.
  • Historically, observed falls were the most compelling evidence supporting the extraterrestrial origin of meteorites.
  • A robust subculture of meteorite hunters has developed along with an associated market for meteorite minerals.
  • Observed fall discoveries are currently the best data source to understand the types of meteorites which fall to Earth. For example, iron meteorites take much longer to weather and are easier to identify as unusual objects, as compared to other types. This may explain the increased proportion of iron meteorites among finds (6.7%), over that among observed falls (4.4%). There is also detailed statistics on falls such as based on meteorite classification.

Martian meteorite falls

Meteorite falls are of particular scientific importance when the meteorite originates from another planetary body. Of the meteorites identified as originating from Mars, only five are classified as observed falls in the Meteoritical Bulletin Database: Chassigny, Shergotty, Nakhla, Zagami and Tissint - only 0.4% of all approved falls are meteorites originating from Mars. Conversely, of the more than 430 recognized Martian meteorites, less than 1.2% are observed falls.

The Martian origin of these meteorites is supported by their mineralogy, chemical and isotopic composition, and by gases trapped within some Martian meteorites whose composition corresponds to that of the Martian atmosphere measured by spacecraft. Observed falls are particularly valuable because they can be recovered soon after arrival on Earth, limiting terrestrial weathering and contamination. The most resent fallof Tissint in 2011 provided unusually fresh Martian material and has been used to investigate the interior, surface and atmosphere of Mars.

Statistics

While the stream of meteorites reaching Earth remains pretty much constant over time, statistics of meteorite falls show a more or less continuous increase in the number of observed meteorite falls from the end of the 18th century until a significant peak in the 1930s. This steady increase has been described as early as 1963 and has been explained with changing social, scientific and technical circumstances. Population growth and higher population density, improving communication, the expansion of scientific institutions, and the increasing organization of meteoritics and greater interest from the general public all raised the likelihood that fireballs would be reported and that fresh meteorites would be deliberately searched for and recovered. The peak during the 1930s also coincides with increased activity by private collectors, especially Harvey H. Nininger and Oscar Monnig who set significant accents in meteorite hunt and research and the foundation of the Society for Research on Meteorites (now known as the Meteoritical Society) in August 1933, with Frederick C. Leonard as the first president and Nininger as secretary.

The decline in the 1940s is explained by the disruptions caused by World War II, which significantly impaired fieldwork, international cooperation, publication activity and the acquisition of collections. The increase in observed falls since the beginning of the 21st century can be attributed to improved technical and organizational capabilities for detection and recovery, particularly through global and regional fireball networks, satellite detections, meteor reporting websites, weather radar observations, the spread of digital cameras and social media as well as the use of metal detectors, drones and coordinated search teams.

Sign in to keep reading

5 more chapters are free with a Lably account.

More in Earth science