resolved · Unscored / disputed
An unknown planet could explain Uranus’s orbital deviations and be found near the calculated sky position.
Source-backed summary; not presented as a verbatim quotation.
Urbain Le Verrier
Astronomer at Paris Observatory · France
The world at the time.
Uranus’s measured motion did not match predictions using the known planets. Le Verrier inverted the gravitational problem to estimate a new planet’s location.
What happened.
Johann Galle observed Neptune on 23 September 1846 near the predicted direction. The successful positional discovery did not establish that every estimated orbital element was correct.
Predicted vs actual.
| Metric | Predicted | Actual | Variance / caveat |
|---|---|---|---|
| Planet existence near search position | Unknown planet | Neptune observed | Confirmed |
The counter-signal.
The mismatch also invited alternatives such as errors in old observations or inadequacy of the gravitational model. The sparse perturbation evidence meant the inferred orbit was not uniquely constrained.
Verdict.
Reasoning: contested · Outcome: right
The existence and search-location prediction succeeded spectacularly. Reasoning remains marked contested because success at one location should not be confused with a completely accurate orbital solution.
Cause of death / explanatory lens.
No cause of death assigned
The lesson.
Which part of a model’s prediction did the confirming observation actually test?
Sources.
- Recherches sur les mouvements d'Uranus, bibliographic recordarchive · 1846 · claim_publication
- Discovery — Neptuneinstitutional · Date not established · outcome
- September 23, 1846: Neptune’s Existence Observationally Confirmedinstitutional · 2020 · claim_date_and_counter_signal
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