2025 Geminids meteors' peak and the rotation of 3200 Phaeton

ATel #17629; Costantino Sigismondi (ICRANet Pescara and APRA-ISF Rome), Federico Manzini (Stazione Astronomica di Sozzago), Virginio Oldani (Stazione Astronomica di Sozzago), Paolo Ochner (UniPd; INAF-OAPd), Maria Salvatori Buzzanca (Liceo Morgagni, Roma)
on 25 Jan 2026; 17:07 UT
Credential Certification: Costantino Sigismondi (sigismondi@icra.it)

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The Geminids (GEM) are presently the most abundant yearly meteor shower, peaking with a Zenithal Hourly Rate ZHR>100 around 13-14 December each year. The parent-body of GEM is an Apollo-family asteroid 3200 Phaethon, rotating in 3.6 hours and with periodical close encounters with Earth. The rotation of the parent nuclei of meteors' shower may leave signatures in the local ZHR near the peak. In the observations from a single site, the presence -during the peak activity- of periods without meteors is frequent and well documented. The gaps without meteors tend to disappear as the meteors counts are extended worldwide, even if nearly simultaneous meteors counts are weighted each with their local instantaneous zenithal radiant distances and the sky limiting magnitude. Averaging over the whole Earth's hemisphere exposed to the meteoroids' flux, may cancel the evidence of structures in the meteoroids' swarm below dimensions of 10000 km. The 2025 GEM meteor shower's peak has been observed worldwide, under favorable lunar phases: reports are available on imo.net. Assuming that the peak's structures are reliably associated to the major jets on the parent body and its rotation period, we analyzed separatedly the meteors recorded in Pescara ICRANet, Rome and Ely (Minnesota, US) on 12-14 December 2025, all nigth long. We found that the bright-meteors gaps and periods including also fireballs, during 2025 GEM peak, are alternated with the same rotation period of 3200 Phaethon. On the parent asteroid a single region may be responsible of the bulk of the ejected meteoroids. (see the attached image obtained by analyzing the video reported in https://www.imo.net/members/imo_photo/view?photo_id=4373)

Structures of 2025 Geminids meteor shower's peak (Ely, MN)