3I/ATLASEvidence
Evidence · 3I/ATLAS
Two telescopes put the radius below 2.8 km
Before perihelion Hubble limited the radius to below 2.8 km and SPHEREx to below 2.5 km, and after perihelion Hubble measured 1.3 ± 0.2 km.
What it means
Openunchanged
Disputedunchanged
What it implies
- Every direct measurement or limit falls below the 2.5-km radius the large-size answer needs.For the key question: How big is the nucleus of 3I/ATLAS?
Next steps 1
1
Fit the last Hubble DD 18152 visits for nucleus size
Could decideFair odds~40 h
10score
Details
The final visits (March to April 2026, beyond 5 au) had the faintest coma. A radius fit with coma subtraction that lands inside 0.35-1.8 km would settle the size; one outside would reopen it. The data are public in MAST.
Ranked by how likely each is to move the key question, for the time it takes
Sources 3
SRC
SRC
Cite it
Mysteries Department. (2026). Two telescopes put the radius below 2.8 km [Evidence EVD0DFQ48E606F6]. https://mysteriesdept.com/r/EVD0DFQ48E606F6
@misc{mysteriesdept_evd0dfq48e606f6,
title = {Two telescopes put the radius below 2.8 km},
author = {{Mysteries Department}},
year = {2026},
note = {Evidence, catalog key EVD0DFQ48E606F6},
url = {https://mysteriesdept.com/r/EVD0DFQ48E606F6}
}