Skip to main content

Celestial Calculations - J. L. Lawrence ***

These days, amateur astronomers don’t need to do any calculations. If their telescope is of the ‘go-to’ kind, they just type in the name of the object they want to observe and the telescope does the rest. If they have an old-fashioned manual telescope, or if they want to see something that isn’t in the telescope’s database – such as the ISS or a satellite – they consult a mobile app or a website. With all these handy software aids, it’s easy to forget that what they’re doing – in a fraction of a second – is a long series of calculations of the sort astronomers used to have to do by hand.

Those calculations are what this book is all about – but before you go running for the hills, there’s no advanced mathematics in it. You’ll scour it in vain for differential equations, complex numbers, logarithms or x-y graphs – for the simple reason that none of those things existed when astronomers started doing the calculations we’re talking about. It does use a few trigonometric functions like sines and cosines – originally developed by the ancient Greek astronomer Hipparchus, not as a sideline but because he needed them for his day job – and anyone can find those buttons on a calculator app even if they’re not sure what they mean.

Some of the things the book shows you how to calculate, particularly in the first few chapters, won’t even look like astronomy to many people. There are calendar and time zone conversions, sunrise and sunset times, and the dates of equinoxes and solstices – but all of these are ultimately based on celestial motions. When the book moves on to the subject of orbits – whether of planets around the Sun or satellites around the Earth – there’s another surprise. The usual approach in popular science books is via Newton’s theory of gravity – but that’s not how J. L. Lawrence tackles it here. That’s because gravity is physics, and that’s not what this book is about. If all you need is a geometric description of orbits, you can find it in the work Kepler, dating from the very beginning of the 17th century – which is as ‘modern’ as the calculations in this book get.

Having written several books myself, I was struck by just how much effort the author must have put into this one. It’s close to 400 pages long, but that’s just the tip of the iceberg. By the very nature of the subject matter, Lawrence didn’t simply have to write words, he had to do calculations – sometimes several on a page. On top of that, the book comes with a suite of downloadable computer programs, which do things like plotting star charts and working out rise and set times for the Moon and planets. Of course, it’s easy enough to find other free software which can do the same things – often in a slicker and more flexible way – but here you get a step-by-step explanation of the logic behind the number crunching.

For the sort of person who is excited by the title Celestial Calculations, this book will be perfect; they can look forward to hours of enjoyment working through the examples. The catch is, I can’t imagine there are many people in that category. For a more general reader interested in popular science or amateur astronomy – and that includes me – the book still provides some fascinating insights, but it’s so long and detailed that reading it often verges on hard work rather than fun. Personally, I would have enjoyed it more if it had been a third of the length.
Paperback 
Kindle 
Using these links earns us commission at no cost to you
Review by Andrew May

Comments

Popular posts from this blog

Philip Ball - How Life Works Interview

Philip Ball is one of the most versatile science writers operating today, covering topics from colour and music to modern myths and the new biology. He is also a broadcaster, and was an editor at Nature for more than twenty years. He writes regularly in the scientific and popular media and has written many books on the interactions of the sciences, the arts, and wider culture, including Bright Earth: The Invention of Colour, The Music Instinct, and Curiosity: How Science Became Interested in Everything. His book Critical Mass won the 2005 Aventis Prize for Science Books. Ball is also a presenter of Science Stories, the BBC Radio 4 series on the history of science. He trained as a chemist at the University of Oxford and as a physicist at the University of Bristol. He is also the author of The Modern Myths. He lives in London. His latest title is How Life Works . Your book is about the ’new biology’ - how new is ’new’? Great question – because there might be some dispute about that! Many

Stephen Hawking: Genius at Work - Roger Highfield ****

It is easy to suspect that a biographical book from highly-illustrated publisher Dorling Kindersley would be mostly high level fluff, so I was pleasantly surprised at the depth Roger Highfield has worked into this large-format title. Yes, we get some of the ephemera so beloved of such books, such as a whole page dedicated to Hawking's coxing blazer - but there is plenty on Hawking's scientific life and particularly on his many scientific ideas. I've read a couple of biographies of Hawking, but I still came across aspects of his lesser fields here that I didn't remember, as well as the inevitable topics, ranging from Hawking radiation to his attempts to quell the out-of-control nature of the possible string theory universes. We also get plenty of coverage of what could be classified as Hawking the celebrity, whether it be a photograph with the Obamas in the White House, his appearances on Star Trek TNG and The Big Bang Theory or representations of him in the Simpsons. Ha

The Blind Spot - Adam Frank, Marcelo Gleiser and Evan Thompson ****

This is a curate's egg - sections are gripping, others rather dull. Overall the writing could be better... but the central message is fascinating and the book gets four stars despite everything because of this. That central message is that, as the subtitle says, science can't ignore human experience. This is not a cry for 'my truth'. The concept comes from scientists and philosophers of science. Instead it refers to the way that it is very easy to make a handful of mistakes about what we are doing with science, as a result of which most people (including many scientists) totally misunderstand the process and the implications. At the heart of this is confusing mathematical models with reality. It's all too easy when a mathematical model matches observation well to think of that model and its related concepts as factual. What the authors describe as 'the blind spot' is a combination of a number of such errors. These include what the authors call 'the bifur