Fireballs

Meteorite fragments of asteroid 2024 BX1 recovered nearby Berlin are aubrites

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On January 21st, 2024, a small (meter-sized) asteroid now designated 2024 BX1 and detected while still in space entered the Earth’s atmosphere near Berlin (Germany). Fragments of the corresponding meteorite have now been found and determined (by Peter Jenniskens and team) to belong to the rare group of aubrites (enstatite achondrites). This meteorite will certainly have an associated orbit and will be added to the list as soon as both its name (from the MetBull DB) and orbit are officially announced.

For more info, see the press release by the SETI institute.

New meteorites with orbits from France and Italy

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Two recent events saw the recovery of meteorites for which there is good data on the entry fireballs: first, the fall of the small (ca. 1 m diameter) asteroid 2023 CX1 in France on February 13th, resulting in the discovery of at least 7 meteorite fragements since. Second, the fall of a meteorite on “Valentine’s day”, February 14th, in southern Italy, and the recent detection of the first meteorite fragments. I expect both events to yield meteorites with reliable orbits, in particular, the first one, which was already observed while still in space. From the look of it, both meteorites look like ordinary chondrites.

New paper accepted: Flensburg (C1-ungr.) in MAPS

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A paper describing the trajectory and orbit of the Flensburg (carbonaceous, C1 ungrouped) meteorite, which fell on September 12th, 2019 in northernmost Germany, has been accepted for publication into MAPS, and the corresponding preprint uploaded on arxiv.org. The meteoroid delivering the single known piece of the Flensburg meteorite (of only 24.5 g) originates from a quite elongated orbit with a large semi-major axis (ca. 2.8 AU), which puts it right on the 5:2 orbital resonance with Jupiter, as well as in the Jupiter Family Comets field (2 < Tisserand parameter <3). It had a mass in the range of 10-20 metric tons and correspondingly, a radius of 2-3 meters. The authors suggest that based on the orbit and the very short cosmic-ray exposure age of only 7 ka (Bischoff et al., 2021), the meteoroid probably originated on a carbonaceous asteroid close to the edge of the 5:2 resonance.

Flensburg is only the fourth carbonaceous meteorite with an orbit (the others being Tagish Lake, Maribo, and Sutter’s Mill). Its interesting to note that carbonaceous meteorites are now slightly over-represented (ca. 11%) among meteorites with orbits compared to their abundance among “normal” finds (ca. 4%), perhaps because, once landed on the surface, they decay quickly and are thus less likely to be found without the “prompt” provided by the fireball observation. /m4

Novo Mesto* – a new meteorite linked to a bright fireball

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novo mesto meteorite
The Novo Mesto* meteorite. (Photo: Bojan Ambrožič / bojanambrozic.com)

In the morning of February 28th, a bright daytime fireball was observed over Slovenia. Now, a fresh, fusion-encrusted meteorite (ca. 200 g), looking like an equilibrated chondrite, has been found in the region where the fragments from the fireball were expected to drop. On March 7th, it was found and reported by Gregor Kos in the driveway of his house, and later confirmed to be a meteorite by Bojan Ambrozic. Later that same day, the meteorite was handed over to the Natural History Museum of Slovenia. The prospective name of the meteorite (not yet approved by the Meteoritical Society, which is why I provide the name with an asterisk) is Novo Mesto*.

Obviously, this is an excellent candidate for a meteorite which will have an associated orbit. /m4

Large fireball in North-Rhine-Westphalia (Germany)

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On March 2nd, ca. 23:38 UTC (0:38 local, i.e., CET), a large fireball was observed over North-West Germany, as the IMO (International Meteor Organization) reports. At an estimated diameter of 2 meters and a mass of about 10 tons (although this is contingent on the assumed entry velocity of 14 km/s and the assumed density of 3000 kg m3). At that size and relatively slow velocity, it seems plausible that some meteorites survived, but again, this depends on the assumptions made. Any meteorites would have fallen to the south-east of the city of Wesel on the Rhine.

Of course, there many meteors falling all the time, but this one seems very well observed (165 observations accross multiple countries!) and also relatively large; furthermore, there are several films of the meteor captured from multiple angles – so it seems likely that in this particular case, if any meteorites are found, they will have a very well-defined orbit. We’ll see if anything interesting (in terms of meteorites, of course!) comes from this – until then, that meteor goes to the candidate list. /m4