# Gaia traceback favours the thin disc and finds no home star

> Tracing 3I back through Gaia DR3 finds 25 stellar encounters within 1 pc, none a plausible host, and strongly favours a thin-disc origin; a second study…

Source: https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ5327B9KS/gaia-traceback-favours-the-thin-disc-and-finds-no-home-star  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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[3I/ATLAS](https://mysteriesdept.com/mysteries/3i-atlas)Evidence

Evidence · 3I/ATLAS

# Gaia traceback favours the thin disc and finds no home star

Tracing 3I back through Gaia DR3 finds 25 stellar encounters within 1 pc, none a plausible host, and strongly favours a thin-disc origin; a second study finds 93 nominal encounters within 2 pc over 10 million years.

Suggestive0

## What it means

Key question[Where in the Galaxy, and how long ago, did 3I/ATLAS form?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0MTPD0FX/where-in-the-galaxy-and-how-long-ago-did-3i-atlas-form)

2 answers, none ahead yet

**Open** unchanged

Answer this evidence bears on[A thin-disc body a few billion years old](https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ335PRDVB/a-thin-disc-body-a-few-billion-years-old)

Supports2 for, none against

**Still possible** unchanged

What it implies
1.

Kinematics alone do not require the thick disc.For the key question: Where in the Galaxy, and how long ago, did 3I/ATLAS form?

## Next steps 1

1

Repeat the stellar traceback with Gaia DR4

Could shiftFair odds~24 h

[On: Where in the Galaxy, and how long ago, did 3I/ATLAS form?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0MTPD0FX/where-in-the-galaxy-and-how-long-ago-did-3i-atlas-form)

**9** score

Details

When Gaia DR4 is released, rerun the backward integration with its larger catalogue and better velocities. A membership probability that moves decisively to thick or thin disc settles which answer leads; a home star within a few parsecs would be a first.

Ranked by how likely each is to move the key question, for the time it takes

## Sources 2

[3I/ATLAS: In Search of the Witnesses to Its Voyage](https://mysteriesdept.com/sources/SRC0DFPWGSFBE9F/3i-atlas-in-search-of-the-witnesses-to-its-voyage)

Pérez-Couto et al. 2025

SRC

[Search for Past Stellar Encounters and the Origin of 3I/ATLAS](https://mysteriesdept.com/sources/SRC0DFPWGSF2F8W/search-for-past-stellar-encounters-and-the-origin-of-3i)

Guo et al. 2025

SRC

## Cite it

```
Mysteries Department. (2026). Gaia traceback favours the thin disc and finds no home star [Evidence EVD0DFQ5327B9KS]. https://mysteriesdept.com/r/EVD0DFQ5327B9KS
```

Key

**EVD** 0DFQ5327B9KS

Kind

Evidence

Tier

Suggestive

Found in

[Session 1](https://mysteriesdept.com/mysteries/3i-atlas/sessions/SES0DFQC03S98K5/session-1-3i-atlas-opened-the-literature-to-november-2026) · 2 Nov 2026

Version

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