3I/ATLASEvidence
Evidence · 3I/ATLAS
JWST: water D/H near 1 per cent and high carbon-13 ratios
JWST measured a water D/H ratio of 0.95 ± 0.06 per cent and 12C/13C of 141 to 191 in CO2 and 123 to 172 in CO, pointing to ices formed below about 30 K around a metal-poor star some 10 to 12 billion years ago.
What it means
Key questionWhat is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?
No answer ahead yet
Openunchanged
Answer this evidence bears onAn icy body from a cold, metal-poor disc around an old star
Supports6 for, none against
Still possibleunchanged
What it implies
- The ices were made colder and in a different chemical environment than the Sun's comets.For the key question: What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?
- An independent, non-kinematic hint that 3I is older than the Sun.For: Where in the Galaxy, and how long ago, did 3I/ATLAS form?
Next steps 2
1
Compare gas lost with crust depth
Could shiftFair odds~20 h
11score
Details
Use the compiled production rates (Frincke and Seligman's table) to date when more than 20 m of surface had gone, and check whether the composition changed then. A change at that point favours the crust; a change well before or after weakens it.
2
Test whether a cosmic-ray crust can raise D/H to 1 per cent
Could shiftFair odds~30 h
8score
Details
Run the cosmic-ray processing model forward to predict how much a 20-m processed crust changes water D/H and 12C/13C. If processing cannot reach the measured ratios, the birthplace reading is strengthened; if it can, the isotopes no longer date the body.
Ranked by how likely each is to move the key question, for the time it takes
Sources 2
SRC
Cite it
Mysteries Department. (2026). JWST: water D/H near 1 per cent and high carbon-13 ratios [Evidence EVD0DFQ3PX0VGG4]. https://mysteriesdept.com/r/EVD0DFQ3PX0VGG4
@misc{mysteriesdept_evd0dfq3px0vgg4,
title = {JWST: water D/H near 1 per cent and high carbon-13 ratios},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DFQ3PX0VGG4},
url = {https://mysteriesdept.com/r/EVD0DFQ3PX0VGG4}
}