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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Meteorite fall | 3/5 | https://en.wikipedia.org/wiki/Meteorite_fall | reference | science, encyclopedia | 2026-05-05T07:53:37.329679+00:00 | kb-cron |
=== Radar detection === Weather radar has become a useful aid for locating meteorites after observed fireballs because it can detect descending fragments of the meteorite during the dark flight-phase – that is, the phase of a meteorite's descent when its speed has been slowed by atmospheric drag to the point that it no longer emits visible light and the fragments reach terminal velocity. Radar-derived echoes from falling stones can help determine whether an observed fireball event has produced meteorites large enough to be recovered on the ground. Radar data in combination with weather data can be used to reconstruct a fall's final trajectory in order to calculate a possible strewn field. This allows people searching for meteorites to focus their search efforts more efficiently than by relying only on traditional methods such as eyewitness accounts, recordings from security cameras and other video sources. Targeted searches have improved the chances to quickly collect minimally weathered specimens that are scientifically valuable for studying the composition and history of their parent bodies. The fall of the Ash Creek meteorite in February 2009 was the first time when data from weather radar was used to locate meteorites on the ground. Among the radar-enabled recoveries of meteorites is also the fall of the Sutter's Mill meteorite. Archived radar data has also been used retrospectively to identify radar signals of falling fragments for earlier meteorite falls such as Worden in 1997 or Indian Butte in 1998. Most of the radar detections of meteorite falls have occurred in the United States, where the data produced by the NEXRAD system is publicly available online almost in real time and archived since the introduction of the system in the 1990s. As of 2025 there are 32 meteorite falls where evidence of falling debris was found in NEXRAD data. The ARES Division of NASA also publishes possible landing zones of meteorite fragments identified by radar stations across the United States. Among them are also falls outside the United States, such as the Grimsby meteorite, a fall from 2009 in Canada and the Viñales meteorite, a fall from 2019 in Cuba, both of which were within the detection radius of NEXRAD stations.
=== Astronomical observations before impact === In October 2008, the observation of asteroid 2008 TC3 turned into the first meteorite whose impact had been predicted. The asteroid on a collision course with Earth had been discovered by Richard Kowalski with the automated Catalina Sky Survey telescope at Mount Lemmon Observatory, about 20 hours before it entered the atmosphere and fell in the Nubian Desert in Sudan. The fall of the meteorite could be observed from a distance of 1,400 km by pilots of a KLM passenger plane flying over Chad and a webcam from a beach in Egypt from a distance of 725 km. Eyewitnesses on the ground in Wadi Halfa and at "train station number six" (Arabic: al-Maḥaṭṭa Sitta) in northern Sudan at 05:46 am local time observed a meteor and heard explosion sounds. Two months after the fall, an expedition organized by the University of Khartoum found the first fragments of the meteorite. The meteorite was named Almahata Sitta - after the train station. Altogether 10.5 kg of the meteorite in some 600 fragments were recovered. Since the observed fall of the Almahata Sitta meteorite, 10 more asteroids have been added to the list of predicted asteroid impacts on Earth which impacted earth after discovery and orbit calculation that predicted the impact in advance. Among them are 3 more observed falls, where fragments of the meteorites could be recovered:
Meteorite Motopi Pan - (Asteroid 2018 LA) Meteorite Saint-Pierre-le-Viger - (Asteroid 2023 CX1) Meteorite Ribbeck - (Asteroid 2024 BX1)
== Historic records of meteors and meteorites ==
=== Meteoric iron === Throughout recorded history, humans have observed meteor showers and fireballs in the sky and occasionally documented these events. Since antiquity there are written records on sporadic meteors from Chinese, Korean, Babylonian, Greek and Roman sources. Due to the distinctive metallurgical properties Meteoric iron was used by cultures worldwide, even before the Iron Age – among them Tutankhamun's meteoric iron dagger, a bronze age arrowhead found in Switzerland and tools made from the Cape York meteorite by Inuit.
=== Philological evidence === Philological evidence suggests that in several ancient cultures the word "iron" was used in connection with the sky, reflecting an awareness that rare iron masses could arrive as meteorites. In Mesopotamia the Sumerian term for iron was an-bar, meaning "fire from heaven" and the parallel Hittite term ku-an also conveys a celestial origin. Egyptian terminology points the same way: The compound expression bia-en-pet that first appeared in the Nineteenth Dynasty of Egypt (13th century BCE) combines the terms for "thunderbolt" and "heaven" and in the meaning for "iron of the sky" was used for iron in general – suggesting an explicit recognition of meteoritic iron. Similar ideas appear in Semitic languages, where Hebrew parzil and Akkadian barzillu derive from barzu-ili "metal of god/of heaven" and the association persists into modern Georgian, where a meteorite is called tsis-natckhi "fragment of heaven".