Review

Full disclosure: I never much cared for Pluto as a planet, and was glad to see it bumped off. Pluto had it coming.

The main story is about how Mike Brown and his team discovered a number of Kuiper belt objects, including one larger than Pluto that would eventually be named Eris, the goddess of strife and discord. As a result of the discovery, and in part owing to Brown’s lobbying, the International Astronomy Union voted to ‘demote’ Pluto from the pantheon of planets. The reason for the demotion was that Pluto simply isn’t much like the other planets; it’s much more like thousands of other planetoids in the Kuiper belt, a huge collection of objects revolving around the sun at a declination of 20 degrees from the planets, with orbits ranging from nearly circular to highly elliptic. Pluto happens to be one of the larger such objects, and has 5 moons. But Brown discovered other objects of roughly the same size as Pluto, including one that is significantly larger (and also has a moon). So the question arose: should all those objects also be classified as planets? If so, just how many ‘planets’ are we willing to acknowledge?

In the end, as we all know, the IAU declared that there are eight planets, and booted Pluto off the list.

But, oddly, it’s not the discovery of Eris that drives this story forward. Brown is mostly telling his own story: a young astronomer who was fascinated by planets and who needed to do something big to ensure he would get tenure. Back in 1992 the Kuiper belt was first characterized, ‘discovered’ in a sense (not by Brown), and eventually Brown got the idea of pointing telescopes at the Kuiper belt to try to find planet-sized objects. To that end he and a team member (David Rabinowitz) wrote software to identify candidate objects, and set up an observational schedule on an obsolete and disused 48” telescope on Mt. Palomar, and, later at the Keck observatory in Hawaii. After a year of coding and years of observation they and their other team member, Chad Trujillo, began finding large Kuiper belt objects.

One in particular, codenamed “Santa” by the team, became embroiled in controversy. The team had discovered this object, and spent some months observing it, in order to prepare a peer reviewed paper describing its properties. They had submitted the title of their paper in preparation for the conference where they planned to present. Three days later a team of Spanish astronomers announced that they had discovered … that same object! Brown was chagrined, of course, but supportive of their claim to discovery, since they announced first. But it soon became apparent that there was something fishy. It turned out that the camera Brown’s team had been using at Mt. Palomar had a website that showed where the camera was pointing and what it was pointing at. During the three days between the time Brown had submitted the title of his paper, which included the interim object designation, and the time of the Spanish astronomers’ announcement, that website had been accessed eight times by computers at the research institute where the Spanish astronomers worked. And the accesses were via searches for the object designation appearing in Brown’s paper’s title.

As an aside, it’s interesting to see how this controversy is reported on the English and Spanish wikipedia sites. In the main English page on Mike Brown the facts of the case are reported more or less as Brown describes them in his book. In the main English page for José-Luis Ortiz the facts are also reported in much the same way (though greatly abbreviated. In the main Spanish page for Ortiz we have a one-sentence version of Ortiz’ side of the story. And finally, in the English page devoted to the controversy we have an account that gives roughly equal weight to the claims of Ortiz and the accusations made by Brown (specifically, that it appears the Spanish team ‘discovered’ the object by Googling the object listed in Brown’s paper).

The two theories are as follows:

Ortiz and team say that they had discovered the object in late July 2005 by looking through photos they had begun taking in 2002. They merely accessed the camera logs to check whether Brown had found the same object, but could not get enough information from those logs to be sure.

Alternatively, you could choose to believe that Ortiz had never seen the object before his grad student Googled the object named in Brown’s paper, and then rushed to report the “discovery”.

Both theories are plausible. But the first theory suffers from the following problems: First, there do not appear to be any logs, emails, or other artifacts that would suggest that Ortiz knew anything about the object prior to the pre-publication of the title of Brown’s paper. Second, Ortiz seems not to have known very much about the object at the time he announced its discovery. For example, he suggested that the object might be larger than Pluto; yet Brown had already established that it was in fact about one third the size of Pluto. Also, Ortiz offered no other observations about the planet (the fact that it has a moon, its albedo, surface composition, etc.) other than its location and orbit - the two pieces of information that could be quickly gleaned by perusal of Brown’s camera logs. Third, at no time did Ortiz volunteer the fact that he had accessed those logs, neither in his correspondence with the Minor Planet Center nor, later, in private correspondence with Brown. It was only after Brown was notified of the camera log access, and after the access was made public when Brown was unable to get Ortiz to respond, that Ortiz attempted any explanation.

Well, you can draw your own conclusions.

Controversy aside, Brown does an excellent job in this book of weaving together his professional life, private life, and the discoveries that he and his team made. It’s quite an enjoyable read, even if you were upset about Pluto’s demotion.

As a final aside, one of the best parts of the book, for me, was Brown’s summation of the debate about what constitutes a planet. The IAU had proposed a bizarre definition that was soundly voted down: spherical things that revolve around the sun. This definition would eventually have resulted in 200 or more qualifying “planets” and would have reinstated a number of objects in the asteroid belt that had been demoted over a hundred years ago. In any case, the definition scarcely captures any interesting or useful concept. Brown proposes that there are in fact four categories of things orbiting the sun: gas giants (four of them), terrestrial planets (also four), asteroid belt objects, and Kuiper belt objects. This makes a lot of sense, in that members of these four categories had similar histories and formed by similar processes and, therefore, provide a useful categorization.

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