Jeremiah Horrocks Observes the Transit of Venus
- When
- 1639
- Where
- Much Hoole; Carr House, Much Hoole
- Episodes
- 2
Jeremiah Horrocks observed the 1639 transit of Venus from Much Hoole, correcting Kepler's predictions to identify the event. He and William Crabtree were the only observers to record it, using the data to estimate the astronomical unit.
Episodes
- Prediction of the 1639 Transit
Horrocks corrected Kepler's calculations to predict the 1639 transit, which Kepler had identified as a near-miss.
- Observation of the Transit
Horrocks and Crabtree observed the transit of Venus on 4 December 1639, the only two recorded observers of the event.
Background and detail
Prediction and Preparation. Horrocks corrected Kepler's orbital calculations, realizing transits occur in pairs eight years apart. This allowed him to predict the 1639 event, which Kepler had listed as a near-miss. By 1638, Horrocks had acquired the best available telescope to prepare for the observation.
The Observation. On 4 December 1639 (Gregorian), Horrocks observed the transit from Carr House in Much Hoole. William Crabtree independently observed the event from Broughton. These were the only two recorded observations of the transit, which appeared as a small black circle moving across the solar disk.
People involved
- Jeremiah Horrocks · Astronomer and primary observer
- William Crabtree · Astronomer and co-observer
Sources
- Jeremiah Horrocks Wikipedia, revision of 2026-09-02
- Transit of Venus Wikipedia, revision of 2026-09-11
Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.