A glowing ring of metal fell to Earth, and no one has any idea what it is
Briefly

Space is increasingly crowded, but large chunks of metal from rockets are generally not flying around in Earth orbit undetected and untracked.
The evidence is marginal for the ring being space debris. The most likely possibility is reentry of the SYLDA adapter from the Ariane V184 flight, object 33155.
Read at Ars Technica
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