For readers who want the full picture
Detailed explanation
If a meteoroid remains stable during part of its flight, an oriented shape with flow lines or a pronounced leading face may develop.
Thumbprint-like depressions are called regmaglypts. They are often clearer on iron meteorites but do not occur on every meteorite.
- Formation
- atmospheric ablation
Interesting, but not proof
Slag or weathered rocks can also show depressions. Orientation and regmaglypts must be assessed alongside material, crust, density and documented provenance.
Oriented flight
A fragment becomes oriented when it maintains a relatively stable attitude during part of ablation. The leading face is eroded more strongly and may become shield- or cone-shaped; melt flows towards the margins and freezes as lines or lips.
Many bodies tumble or change attitude after fragmentation. Fully oriented meteorites are therefore rare, while partial orientation is more common. Orientation describes flight shape, not material class or origin.
Regmaglypts and their diagnostic limits
Regmaglypts are thumbprint-like hollows produced by uneven ablation and turbulent flow. They are conspicuous on many iron meteorites but can occur on other types or be absent altogether.
Slag, corroded metal and naturally weathered rock can show similar hollows. Shape, edges, fusion crust, internal texture, density and chemistry must be considered together; one apparent thumbprint is not proof.
Short & simple
The essentials in 30 seconds
- Shapes and depressions that can develop during atmospheric ablation.
- If a meteoroid remains stable during part of its flight, an oriented shape with flow lines or a pronounced leading face may develop.
- Thumbprint-like depressions are called regmaglypts. They are often clearer on iron meteorites but do not occur on every meteorite.
Sources & editorial note
Sources & databases
Editorially paraphrased prefill, reviewed 12 August 2026. The linked sources support further specialist verification.