Jeremiah Horrocks was born in 1619 in Toxteth, Liverpool. He was born into a poor family, who were deeply religious Protestant Puritans, (Father of British Astronomy 1). His father, James Horrocks, was a watchmaker, and his mother was the former Mary Aspinwall. Jeremiah spent his childhood in Toxteth Park, before moving to a small village in the proximity of Liverpool, (Horrocks, Jeremiah 1).
The seventeenth century had a belief system of their own. Many people believed in magic and witchcraft at the time, as there were no scientific laboratories to conduct real research about the earth and the heavens. Therefore, there was no organized scientific research, and only the well educated knew that the Earth was round. Not much else was known about astronomy besides that though. Since Horrocks lived in Protestant England, it wasn’t necessarily heretical to think that Earth orbited the sun, like most Italians believed, but it still seemed like a fairly radical belief to some people, (Father of British Astronomy 2). Labour was necessary to establish more observations about astronomy, (Jeremiah Horrocks and His Opera Posthuma 1). It could have been called the reconstruction of Astronomy, (Jeremiah Horrocks and His Opera Posthuma 1). Jeremiah contributed greatly to this movement by making many observations, and by challenging the theories of some famous astronomers.
Jeremiah Horrocks was a theorist, and he was a very cautious observer. During his short lifetime, he paid much attention to the works of both Johannes Kepler, and that of Tycho Brahe. He was eventually able to figure out ways to eliminate observational errors. And, Horrocks carried on the work of Tycho by using a telescope to enhance the findings. He was able to redetermine the astronomical constants for many planets, correct the scale of the solar system, improve the theory of lunar motion, study the motions of planets, and conduct a detailed study of the tides, (Horrocks, Jeremiah 2-3).
Horrocks was an intelligent student, and at the age of fourteen, he got into Cambridge University. His college time lasted for three years, and by that time, he had become well educated in Greek, Latin, and the Scriptures., (Father of British Astronomy). Although he worked as a sizar for his maintenance, he left Cambridge without receiving a degree. So, he decided to teach astronomy to himself, and he became acquainted with the astronomical works of contemporaries, (Horrocks, Jeremiah 1). He also became a tutor at Toxteth, where he devoted his time towards astronomical observations, (Jeremiah Horrocks 1).Then, he moved to Much Hoole, Lancashire, where he became a curate at his local church, St. Michaels, (Father of British Astronomy 1).
After departing from Cambridge University, he became acquainted with William Crabtree, who at the time was a merchant in Broughton, which is near Manchester. He had studied astronomy for many years, and the two wrote to each other about astronomical matters up until Horrocks’ death, (Horrocks, Jeremiah 2).
Jeremiah Horrocks was a disciple of Johannes Kepler, a major German astronomer. He agreed with many of Kepler’s ideas, such as that planets had elliptical orbits, and that planets move more rapidly at perihelion than at aphelion. And, Horrocks studied Kepler’s creation of celestial dynamics, and decided to make a dynamical model of his own. He corrected some of the weak features of Johannes Kepler’s model, starting out with rejecting Kepler’s idea that each planet has opposite sides “friendly” and “unfriendly” to the sun, which makes it attracted and repelled in the different parts of its orbit, causing them to move in an ellipse. Horrocks made an analogy to a pendelum, to show that planets can be seen as having a tendency to fall toward the sun, or to go about it freely, just as a pendulum does. His analogy helped to support the idea that the planets always tend to be attracted to the sun and never to be repelled by it, which contradicted what Kepler had believed. Using his conception of gravitation and his theory of comets, he predicted that cometary orbits were elliptical. And, he was able to redetermine the apparent diameters of many celestial bodies. Horrocks reduced Kepler’s estimate of the solar eccentricity, and subtracted from the roots of the sun’s mean motion. After discovering that there were irregularities in the motions of Jupiter and Saturn, he proposed corrections to the Rudolphine Tables, (Horrocks, Jeremiah 7-10).
Jeremiah also read up on the planetary motion laws of Johannes Kepler. Johannes correctly predicted the Venus Transit of 1631, without any record of anybody to have witnessed it, and then went on to predict that another one would occur in 1756. But, Jeremiah didn’t agree with his calculations. So, Horrocks went on to make out that Venusian transits occur in pairs, eight years apart, then either 105 or 121 years later. This would mean that the next one would be visible from Europe, and would occur in 1639, rather than in 1756 as Kepler had predicted. Horrocks was soon proven correct, which was a big deal that a man of twenty disagreed with a famous astronomer, and then was right with his assertion. Using his own data, Horrocks was able to calculate the sizes of the sun and of other planets in the solar system. He found that the sun was huge, and was also able to show that Jupiter and Saturn were giants, which went against the belief that the earth was the greatest creation, (Father of British Astronomy 3-4).
Then, in 1638, Jeremiah Horrocks confirmed Galileo’s discovery of Jupiter’s four moons. He was also able to come to the conclusion that planets shine because of reflected light, and that comets are mere visitors to our solar system. Before he turned twenty, he was able to make tidal observations, leading him to come up with his own theory of gravity, long before Newton came up with his theory, (Father of British Astronomy 6).
In November of 1639, the first transition of Venus across the face of the sun since the telescope was invented was to occur. Only Jeremiah Horrocks and William Crabtree knew that it was going to happen. Horocks observed that, as he focused the sun’s disc onto a piece of card and traced around it, there was a small black spot (which was Venus) starting to edge across the solar disc. He watched the black circular shape center itself on the sun’s disc, so that the limbs of the sun and Venus coincided with each other, which formed an angle of contact, (Father of British Astronomy 7-10).
Jeremiah Horrocks made major contributions to the lunar theory. He included in it the assumptions that the lunar orbit was elliptical an that many of the moon’s inequalities are caused by the pertubative influence of the sun. He also contributed his studies of moon phases, following Tycho Brahe. Horrocks was then able to make improvements in the constants for several lunar inequalities. His most significant accomplishment in lunar theory was that he accounted for the second inequality of longitude by an unequal motion of the apsides and a variation in eccentricity. But, Jeremiah died a year and two months after his historic observation of the Venus Transit, in January of 1641. But his work lived on through William Crabtree and his family. His conclusions were widely circulated, and tested by many. Jeremiah Horrocks soon became known as the Father Of British Astronomy, (Horrocks, Jeremiah 14-16).
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