# Porous aggregates of tiny, weakly absorbing grains

> Still possible: The dust is made of porous aggregates of sub-micron, weakly absorbing grains, which produce a deep, narrow negative polarisation branch.

Source: https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ19DTND2G/porous-aggregates-of-tiny-weakly-absorbing-grains  
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)[What kind of dust gives 3I/ATLAS its unusually deep negative polarisation?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0STJE1SH/what-kind-of-dust-gives-3i-atlas-its-unusually-deep-negative)Answer

Answer · 3I/ATLAS

# Porous aggregates of tiny, weakly absorbing grains

The dust is made of porous aggregates of sub-micron, weakly absorbing grains, which produce a deep, narrow negative polarisation branch.

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

## Where it stands

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

## What it predicts

- The polarisation curve does not change as activity changes
- Light-scattering models of such aggregates reproduce the branch depth and width

## What would rule it out

- Laboratory or model aggregates of this kind cannot produce a minimum below -2 per cent

## Evidence 1 for · none against

[Polarisation unchanged across perihelion, fitted by porous aggregates](https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ475QVY2W/polarisation-unchanged-across-perihelion-fitted-by-porous)

Supported

FOR

## The questions it answers

[What kind of dust gives 3I/ATLAS its unusually deep negative polarisation?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0STJE1SH/what-kind-of-dust-gives-3i-atlas-its-unusually-deep-negative)

Part of [What is 3I/ATLAS made of, and why is its chemistry so unlike a Solar System comet's?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0HS0K7SD/what-is-3i-atlas-made-of-and-why-is-its-chemistry-so-unlike)

OpenNo answer ahead yet

## Cite it

```
Mysteries Department. (2026). Porous aggregates of tiny, weakly absorbing grains [Answer ANS0DFQ19DTND2G]. https://mysteriesdept.com/r/ANS0DFQ19DTND2G
```

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**ANS** 0DFQ19DTND2G

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Answer · hypothesis

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[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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