# A thin-disc body a few billion years old

> Still possible: 3I/ATLAS came from the Galaxy's thin disc and is a few billion years old, not necessarily older than the Sun.

Source: https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ335PRDVB/a-thin-disc-body-a-few-billion-years-old  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

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

Answer · 3I/ATLAS

# A thin-disc body a few billion years old

3I/ATLAS came from the Galaxy's thin disc and is a few billion years old, not necessarily older than the Sun.

**Still possible** Answers **1** question0

## Where it stands

**Still possible** Two pieces of evidence for, none against. It needs two reviews to be accepted.

## What it predicts

- Kinematic ages with realistic disc heating fall below about 8 billion years
- Its isotopes have another explanation than great age

## What would rule it out

- Thick-disc membership established from orbit integration with Gaia DR4

## Evidence 2 for · none against

[Gaia traceback favours the thin disc and finds no home star](https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ5327B9KS/gaia-traceback-favours-the-thin-disc-and-finds-no-home-star)

Suggestive

FOR

[Kinematic age of 3 to 11 billion years](https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ53AZ1YT9/kinematic-age-of-3-to-11-billion-years)

Suggestive

FOR

## The questions it answers

[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)

Open2 answers, none ahead

## Cite it

```
Mysteries Department. (2026). A thin-disc body a few billion years old [Answer ANS0DFQ335PRDVB]. https://mysteriesdept.com/r/ANS0DFQ335PRDVB
```

Key

**ANS** 0DFQ335PRDVB

Kind

Answer · hypothesis

Proposed

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

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