Five top books on the early history of astronomy

Dava Sobel is the bestselling author of Longitude, Galileo’s Daughter, and The Planets, coauthor of The Illustrated Longitude, and editor of Letters to Father. Her latest book is A More Perfect Heaven: How Copernicus Revolutionized the Cosmos.

One of five books on the early history of astronomy she discussed with Daisy Banks at The Browser:

The Copernican Question
by Robert S Westman

With your next book we are continuing with Copernicus. This time you have chosen The Copernican Question by Robert Westman.

Robert Westman was interested in exploring the idea that Copernicus was also an astrologer as well as an astronomer. For many years people thought that Copernicus paid no attention to astrology. But in his day, if you were an astronomer you were also an astrologer. Why else would you care about the positions of the planets? But he never wrote about astrology.

Why do you think Copernicus never mentioned the topic of astrology in his writings?

Well, this is what Westman tries to figure out and one of the explanations he gives is that he was planning to write a second book about astrology in addition to his book on astronomy. Copernicus in many ways modelled On the Revolution on a very famous Greek text by Ptolemy. Ptolemy wrote several books – one was just about the planets, where he tried to work out their position, and then he wrote a separate book on astrology. Westman thinks that perhaps Copernicus had that same intention but he never got around to writing the other book. There is a lot of evidence that ties him to other astrologers which is all believable and convincing. So I personally find this idea fascinating. Westman is so good on the detail he goes into – to work out whether his theory is plausible or not. He looked at all the people that Copernicus might have known and explored their ties to astrology. And I thought he made a convincing argument.

You have also written about Copernicus. Why, for you, is he such an important person in the history of astronomy?

Because he had the courage to go against common wisdom and common sense. It is hard today to imagine what a strange idea he entertained. I also like the fact that instead of just imagining it he also spent years making observations in the night sky to try to back up his theory. Remember, he didn’t have a telescope or any instrument with lenses; he was just using the naked eye. All of this was a question of mapping the positions of the planets. I think it must have seemed crazy to him to expect the stars to spin all the way around the earth every 24 hours. It makes much more intuitive sense in terms of size and distance to have the earth move. But then you have the problem of the earth moving, which everyone thought was ridiculous.

Read about another book Sobel discussed at The Browser.

Read about Sobel's heroine from outside literature.

See Sobel's five best list of books which record extraordinary journeys of discovery.

The Page 99 Test: A More Perfect Heaven.

--Marshal Zeringue