3I/ATLASEvidence
Evidence · 3I/ATLAS
CO most abundant by December; methane appears late
By 22-23 December 2025 CO was the most abundant gas, with water and CO2 each about 40 per cent of it, and methane was detected for the first time in an interstellar object only in mid-December.
What it means
Key questionWhy did 3I/ATLAS's activity and chemistry change so much across perihelion?
No answer ahead yet
Openunchanged
Answer this evidence bears onHeat reached deeper, water-richer layers and icy grains
Supports2 for, none against
Still possibleunchanged
What it implies
- Volatile ices that were not active inbound became active after perihelion.For the key question: Why did 3I/ATLAS's activity and chemistry change so much across perihelion?
- The bulk composition differs from the inbound surface.For: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?
Sources 2
SRC
The Volatile Inventory of 3I/ATLAS as seen with JWST/MIRI
SRCBelyakov et al. 2026
Cite it
Mysteries Department. (2026). CO most abundant by December; methane appears late [Evidence EVD0DFQ54XAFGSW]. https://mysteriesdept.com/r/EVD0DFQ54XAFGSW
@misc{mysteriesdept_evd0dfq54xafgsw,
title = {CO most abundant by December; methane appears late},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DFQ54XAFGSW},
url = {https://mysteriesdept.com/r/EVD0DFQ54XAFGSW}
}