The Transit of Venus: The Brief, Brilliant Life of Jeremiah Horrocks, Father of British Astronomy

The accomplishments of Jeremiah Horrocks, as depicted in this book, are truly astounding. The author carefully reconstructs Horrocks' genealogy, his brief life and his ground-breaking work in astronomy, amidst the backdrop of seventeenth century England. The book is well-written, clear and engaging. Less appealing to me was that the book contains many passages reproduced in the original old English. This slowed me down a bit since I found them cumbersome due to the different spelling and sentence structure characteristic of the period. On the other hand, this may be inevitable, at least to some degree, because of the book's subject matter. Overall, this is an interesting read that would likely be particularly appealing to astronomers at all levels.

Isaac Newton famously said, "If I have seen further than others before me, it is because I have stood on the shoulders of giants." Newton was not always so quick to acknowledge his debt to his fellow scientists, but everyone knows the remark could apply to indisputable giants like Galileo and Kepler. However, he also would have meant a giant who has, almost three centuries later, become almost an unknown within the history of astronomy. In _The Transit of Venus: The Brief, Brilliant Life of Jeremiah Horrocks, Father of British Astronomy_ (Weidenfeld & Nicolson), Peter Aughton, who has written before on the voyages of Captain Cook and on Newton, puts Horrocks into his rightful place. It would be too much to say that he gives us a full picture of Horrocks and his work, for the mass of materials about the astronomer is just too meager. However, Horrocks was a brilliant astronomical observer and theoretician, and Newton knew it then as we should now. There was in June 2004 a transit of Venus, only the fifth since Horrocks watched his in 1639. A transit occurs when Venus seems to cross the face of the Sun, and was important in those days because it could be used to calculate how far the Sun was from the Earth. He studied Kepler's work at college in Cambridge, and trusted Kepler, but not blindly; he discovered that Kepler, who had correctly predicted a 1631 transit of Venus, had mistakenly missed a transit that was coming in 1639. Horrocks only realized this with a month to spare, but he was ready to trace the planet crossing the Sun; he did so by training his telescope on the Sun and projecting the picture upon a screen within a darkened room. It was his mathematical analysis of the movements and timing of what he had seen that enabled him to confirm that Venus was moving in an elliptical orbit around the Sun, just as Kepler's laws had implied. However, a clear view of the planet crossing the solar disk showed it to be much smaller than Kepler had thought, and the calculated distance between the Earth and the Sun was far larger than any previous astronomer had come close to considering. Copernicus had estimated the distance to be 7.5 million kilometers, Kepler 22.1, and Horrocks weighed in with 95.4. Even then, he was well below the real figure of 149, but it can be said without exaggeration that he was the first man who had an inkling of how big the solar system really was. Horrocks wrote up his account of the transit, and also went on to show that the Moon tracked an elliptical, not circular, path around the Earth, although the path of the Moon wobbled irregularly due to the gravity of the Sun. He also showed that Saturn and Jupiter were vastly larger than the Earth. Astonishingly, he made these discoveries when he was only twenty-two; only a year later in 1641 he was dead. There is no evidence about the cause of his death. His account of his researches was not published until 1662, and he was belatedly recognized as a genius by