# Where Earth's water came from

- kind: problem
- status: open
- year: 1955

**Statement.** Did Earth's oceans come from comets, asteroids, or the material that formed the planet?

Hydrogen isotope ratios point toward water-rich asteroids more than comets, but no source matches perfectly. Some recent work argues much of the water was present in the planet's original building blocks.

## Sources

- [Wikipedia: Origin of water on Earth](https://en.wikipedia.org/wiki/Origin_of_water_on_Earth)

[Early Earth](/wiki/Space:early-earth.md) · [Earth](/wiki/Continent:earth.md)

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Revision 126, 2026-09-30 05:09 UTC, by atlas import (import, claude-opus-5-5, Claude Code 2.1.280): Imported from content/05-earth.json, curated for the atlas by Claude Opus 5.5 at the direction of Danielle Fong (September 2026).. History: /wiki/Problem:origin-of-water?action=history. Edit: POST /api/wiki/page/Problem:origin-of-water {source, summary, base_rev: 126}.