A lot has already been written about the Neptune affair. It goes like this; in 1781 William Herschel discovers a comet-like object in the constellation of Gemini. It turns out to be a new planet, Uranus. Fifty years later, in the meantime during which several minor planets have been found between the orbits of Mars and Jupiter, it is realised that Uranus is behaving oddly. It wasn’t just where Newtonian / Keplarian gravitational and orbital theory said it should be. Along comes a shy Cambridge mathematical whiz kid, John Couch Adams, who proposes that Uranus is being influenced by the gravitational attraction of a trans-Uranian planet and proceeds to calculate where in the sky it’s to be found. The Astronomer Royal, George Biddle Airy, ignores JCA’s request to search for it and so, in September 1846, the prize goes to France and Germany in the guise of Le Verrier, Galle and D’ Arrest who respectively compute the position of the new planet and then find it, to the chagrin of British astronomy.

As said, a lot has been written about the Neptune affair but until now nothing so even-handed as Tom Standage’s new book.

There is something to be said for a well-informed science journalist writing an unbiased account of a rather specialized subject for what I assume is a general readership.  His Neptune story is well presented and the scientific-political intricacies of the time easily followed. Tom Standage hits the nail squarely on the head in describing an unfortunate episode that could have gone in favour of UK astronomy, but didn’t.  It was, nevertheless, a supreme example of computational dexterity on both sides of the Channel and Standage describes the situation with paramount skill.  Couch Adams wouldn’t say ‘boo’ to a goose but Le Verrier didn’t hide his light behind anybody’s bushel. Both calculated the position of the unseen planet with remarkable accuracy but were beholden to the telescopists to find it for them.

John Couch Adams and Urbain Le Verrier were masters of theoretical orbital mechanics but neither were observers. It needed an eye at the telescope to find the planet that both predicted.  Here the fundamental dissimilarities between UK and European national astronomy held sway. Although Couch Adams approached Airy for help, it was not the job of the Astronomer Royal to look for new planets. His was the task of compiling star positional tables for navigation. But on the Continent, professional astronomers were paid to study the heavens and they had more freedom to divert resources to the task and had well equipped public observatories to do it.  After Le Verrier’s preliminary reductions of the position, the new planet was ripe for the picking. So, on 23^rd September 1846,with the express permission of the Director, Encke, the planet Neptune fell to Johann Galle and Heinrich d’ Arreste using the Faunhofer refractor at the Berlin observatory.

A scandal erupted in England as to why we hadn’t found the new planet but to no avail. The prize was lost and Airy was to blame. It is certainly true that Airy had a lot of egg on his face, to the extent that even that doyen of the mid-19^th century scientific community, Sir John Herschel, failed to justify the cock-up. But while it is easy for the reader to take sides, Tom Standage quickly shows that there were mitigating circumstances wherein Airy should not be the scapegoat, if any were in fact needed. It was easy for the British public to criticize the establishment but the work of university observatories and the Astronomer Royal was clearly defined – and it didn’t include looking for planets as a young, largely unknown mathematician wanted them to do.  Herein lies the strength of this book, which presented to this reviewer a refreshingly complete explanation of the affair, untarnished by any bias in deference to previous interpretations, of which there have been several.

The Neptune File is well written and is certainly recommended to anyone interested in astronomical history and planetary discovery. Although unlikely to be the definitive work on the Neptune scandal, because it is clearly aimed at non-technical readership,  it is nevertheless a good overview for the layman and amateur astronomer.

I have a few criticisms; one being that the book deserved to be better produced and is too cheap as a result.  More illustrations would have been welcome; proper photographs, not just poorly reproduced pictures and line diagrams. Neither Neptune nor Uranus is depicted; they should be.  More importantly, although there is some reference (p106) to a new Berlin star chart that enabled Galle and D’Arrest to compare the objects around the predicted position with those seen through the 9-inch Fraunhofer telescope, Standage gives no details at all. For the record, this was Chart XXI of Carl Bremiker’s atlas, showing stars to 9^th magnitude, without which it would have been necessary to plot all the stars seen and to watch for one to change position – exactly what Challis had been doing at Cambridge. The Bremiker chart was crucial to the Berlin discovery and saved days of painstaking work. Le Verrier’s calculated position, RA 21hrs 46mins, Dec -13deg 24min was within one and a half degrees of where the new planet was found, ca RA21hrs 50mins, -13deg 40min . Again, these relevant details are not stated except, rather obliquely, in a series of poorly captioned star charts, that appear to be home-produced from planetarium software augmented by a bit of image-processing, in chapter 7.

The Neptune File ends with a comprehensive summary of recent discoveries of planets orbiting other stars but I felt that, although interesting, this was unnecessary and irrelevant to the main meat. This subject deserves its own book.  Notwithstanding, The Neptune File is a great read and will be a welcome addition to the amateur astronomer’s bookshelf or to the astronomy section of any public library.

Kevin Kilburn, F.R.A.S.