Nick Lomb’s Transit of Venus 1631 to the Present is the best illustrated astronomy book for general readers since Terence Dickinson and Alan Dyer’s The Backyard Astronomer’s Guide. Everything about Lomb’s book from its eye seizing cover, rarely seen historic photographs and charming well researched commentary is first class. Transit is the type of work you steal1 from and frankly, there is no better endorsement than that. I’m not the only reader to reach this conclusion check out this and this and this.
When prowling our few remaining bookstores I often skip illustrated works. Usually they’re dumbed-down rehashes of familiar material but, in Transit’s case, I learned something on my first randomly browsed page. The chapter introduction for Venus of the South Seas reads:
Sometimes scientific expeditions have unintended consequences. The desirability of observing the 1769 transit from the South Seas began a chain of events that would lead to the founding of the colony of New South Wales by the British in January 1788. In effect, modern Australia owes its existence to a celestial event.
How about that history haters. I knew why astronomers cared about transits of Venus. In 1677 Edmond Halley, of Halley’s Comet fame, described a method for calculating the astronomical unit from transit of Venus timings. Venus is close enough to the Earth that its track over the Sun differs for widely separated terrestrial observers. This is the familiar parallax effect. From this small difference you can determine the astronomical unit and if you know the astronomical unit Kepler’s third law tells you the distance of every planet in the solar system. This was a huge payoff for 17th, 18th and early 19th century astronomers. This is what got Cook out in the Pacific. It’s a great story and Lomb’s telling is the best you will find.
1. I’ve picked up a few page design ideas.↩︎