# Heat reached deeper, water-richer layers and icy grains

> Still possible: As 3I/ATLAS neared the Sun, heat reached deeper, water-richer ice and released icy grains into the coma, so the gas changed from…

Source: https://mysteriesdept.com/mysteries/3i-atlas/answers/ANS0DFQ349ZM4Y8/heat-reached-deeper-water-richer-layers-and-icy-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)[Why did 3I/ATLAS's activity and chemistry change so much across perihelion?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0NWRSHDV/why-did-3i-atlass-activity-and-chemistry-change-so-much)Answer

Answer · 3I/ATLAS

# Heat reached deeper, water-richer layers and icy grains

As 3I/ATLAS neared the Sun, heat reached deeper, water-richer ice and released icy grains into the coma, so the gas changed from CO2-dominated to water- and CO-dominated.

**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

- The change follows heliocentric distance on both legs, not time
- Icy grains in the coma fade after perihelion

## What would rule it out

- Composition returns to the inbound CO2/H2O ratio at the same distances outbound

## Evidence 2 for · none against

[CO most abundant by December; methane appears late](https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ54XAFGSW/co-most-abundant-by-december-methane-appears-late)

Supported

FOR

[Water took over near perihelion; the ice band vanished](https://mysteriesdept.com/mysteries/3i-atlas/evidence/EVD0DFQ54QY5WR5/water-took-over-near-perihelion-the-ice-band-vanished)

Supported

FOR

## The questions it answers

[Why did 3I/ATLAS's activity and chemistry change so much across perihelion?](https://mysteriesdept.com/mysteries/3i-atlas/questions/QST0DFQ0NWRSHDV/why-did-3i-atlass-activity-and-chemistry-change-so-much)

OpenNo answer ahead yet

## Cite it

```
Mysteries Department. (2026). Heat reached deeper, water-richer layers and icy grains [Answer ANS0DFQ349ZM4Y8]. https://mysteriesdept.com/r/ANS0DFQ349ZM4Y8
```

Key

**ANS** 0DFQ349ZM4Y8

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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