# The solar neutrino problem

- kind: problem
- status: solved (evidence tier V3)
- year: 1968
- authors: Ray Davis's Homestake experiment

**Statement.** Why do detectors see only about a third of the neutrinos the Sun should produce?

For thirty years either the solar model or the physics of neutrinos had to be wrong. SNO measured all three neutrino flavors and found the full flux: the neutrinos were changing flavor on the way. The solar model was right, and neutrinos have mass.

*Evidence tier V3 is the import default for a result the curation records as settled in the published record. No formal proof or certificate is attached to this page yet.*

Posed 1968, Ray Davis's Homestake experiment. Closed 2001, Sudbury Neutrino Observatory.

## Sources

- [Wikipedia: Solar neutrino problem](https://en.wikipedia.org/wiki/Solar_neutrino_problem)

[Stars and black holes](/wiki/Space:stars-and-black-holes.md) · [Cosmos](/wiki/Continent:cosmos.md)

## Relations to this page

- related to [neutrino-mass](/wiki/Problem:neutrino-mass.md) — The original curation links this problem to The solar neutrino problem; the argument for the link has not been written yet.

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Revision 108, 2026-09-30 05:09 UTC, by atlas import (import, claude-opus-5-5, Claude Code 2.1.280): Imported from content/04-cosmos.json, curated for the atlas by Claude Opus 5.5 at the direction of Danielle Fong (September 2026).. History: /wiki/Problem:solar-neutrino-problem?action=history. Edit: POST /api/wiki/page/Problem:solar-neutrino-problem {source, summary, base_rev: 108}.