A Liverpool Exemplar - Jeremiah Horrocks

An imagined image of Horrocks observing the transit of Venus

Jeremiah Horrocks was born in 1619 at Lower Lodge Farm in Toxteth Park, Liverpool. His father James had moved to Toxteth Park to be apprenticed to watchmaker Thomas Aspinwall and subsequently married his master's daughter Mary. Both families were well educated Puritan and Jeremiah was baptised at the Ancient Chapel of Toxteth, but with their unorthodox beliefs excluding them from public office, by 1600 the Aspinwalls had become a successful family of watchmakers. Jeremiah was introduced early to astronomy and made his own specialist instruments for the study of astronomy. He helped with the family business by day and, in return, the watchmakers in his family assisted in the design and construction of instruments for him to study the stars at night.

He entered Emmanuel College, Cambridge, on 11 May 1632 as a Sizar which means that he did not have the means to support himself and was given specific menial duties to compensate for a reduction in the fees. Having studied mathematics and astronomy in his own time, he left Cambridge in 1635 and returned to Toxteth Park where he became minister at the little chapel and was schoolmaster to his little flock. He did not graduate at Cambridge, but this is consistent with his financial status and many poor students left university without a degree since they could not afford the cost of graduation. Now committed to the study of astronomy, Jeremiah began to collect astronomical books and equipment and in 1635, having dismissed Lansberge's tables as inaccurate, and combined with his friend and correspondent William Crabtree turned to Kepler's tables. These had been published in 1627 and by comparing the theoretical positions with his own observations Jeremiah realised that these were by far the most accurate tables that were founded on a correct planetary theory. However he rejected Kepler's theory of why the planetary orbits were ellipses, which was based on alternate attraction and repulsion of a planet by the sun. Jeremiah then proposed that the planets had a tendency to fall towards the sun. Kepler’s tables had predicted a near-miss of a transit of Venus in 1639 but, having made his own observations of Venus for years, Jeremiah predicted a transit would indeed occur.

By 1638 he owned the best telescope he could find as, with Liverpool being a seafaring town, basic navigational instruments were easy to find. However there was no market for the very specialised astronomical instruments he needed, so his only option was to make his own. He was well placed to do this with the family watchmakers' expertise in creating precise instruments. So he helped with the family business by day and, in return, the watchmakers in his family supported his vocation by assisting in the design and construction of instruments to study the stars at night

By 8 June 1639 he had left home and was in the village of Much Hoole, near Preston, supporting himself as a curate and acting as a tutor to the children of the Stones family, living in Carr House, a substantial property owned by the family who were prosperous farmers and merchants. It was here he witnessed the first transit of Venus and carefully noted the progress of the phenomenon during half an hour before sunset. In 1640 he returned to Toxteth where he wrote 'Venus in Sole Visa' ( Venus Seen on the Sun). Although he is best known for his observations of the transit of Venus in 1639, his most important work was his lunar theory. He realised that the moon's orbit was perturbed by the sun and was able to give a lunar theory which was much better than anything available at the time. In fact his lunar theory was used for around 100 years, a remarkable achievement. He had anticipated Isaac Newton in suggesting the influence of the Sun as well as the Earth on the Moon's orbit and Newton has acknowledged Horrocks's work in relation to his theory of lunar motion. Jeremiah was indeed the first person to demonstrate the Moon moved around the Earth in an elliptical orbit. In the final months of his life he made detailed studies of tides in attempting to explain the nature of lunar causation of tidal movements and became recognised as 'The Father of English Astronomy.'

A plaque in the Ancient Chapel of Toxteth

Jeremiah died aged 22 suddenly on the 3rd of January 1641 and is remembered on a plaque in Westminster Abbey with the lunar crater 'Horrocks' also named after him. Gerard Gilligan, chair of the Society for the History of Astronomy said, "Sadly, he only lived to 22 and had he lived longer he might have outshone Sir Isaac Newton."

In 1859 a marble tablet and stained-glass windows commemorating him were installed in the Parish Church of St Michael, Much Hoole and Horrocks Avenue in Garston, Liverpool is also named after him. Preston's University of Central Lancashire has named its mathematics, physics and astronomy facility the Jeremiah Horrocks Institute; and likewise its smaller observatory in the city's Moor Park is named after him.

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