Thursday, December 17, 2009

A literature review of Pluto

Posted by Darin Hayton on 12/17 at 10:15 PM

As the International Year of Astronomy comes to a close, it is perhaps fitting to spend the last few weeks looking at some recent astronomy and history of astronomy literature. In particular, I am going to look at some of the recent work that confronts the question of Pluto’s planetary status. I am not (yet) taking sides on the question of Pluto’s status. I would rather use this space to examine some of the arguments for and against its demotion from planet to big icy chunk of space debris.1

I was prompted to read some of this literature after a conversation with an astronomer, who agrees with Pluto’s demotion, and a couple students, who think some egregious crime has been committed. As someone who rarely thinks about Pluto, I decided to do a little reading on the subject.

The basic controversy is now well known:
In 2006 a subset of IAU members voted on and passed a resolution that changed the definition of a planet. The new definition excluded Pluto as well as a number of other similar objects.2 Some members of the astronomy community as well as the general public were upset.3 Other astronomers appeared to be perfectly happy with the new definition. The IAU convened again in 2009 and, much to the disappointment of some people, did not revisit the definition of a planet or Pluto’s status.

Pluto seems to be a perennial topic. In addition to the numerous articles and books that have appeared since its reclassification in 2006, dozens of other articles and books had previously been written alternately celebrating and denigrating it. Questions of its planetary status have ebbed and flowed as astronomers learn more about the planet. A flurry of activity in 1956 seemed about to reclassify Pluto as a former moon of Neptune.4 Subsequent calculations in 1964 seem to indicate that Pluto had never been a Neptunian satellite and thus rescued Pluto from the solar system dustbin.5

This series of posts is not meant to decide Pluto’s fate, or even to weigh in on one side or the other. It is, instead, something of a literature review. I am less interested in Pluto’s status than I am in how and why people have argued for one classification or another. I will start with some recent books on the subject and slowly work back to older literature as well as articles.

1I fear I might be opening a can of worms with these posts. I want to stress, again, that these posts surveying the literature on Pluto are not meant to take sides. I will, almost certainly, express my thoughts. But for now I merely want to analyze what others have said.
2The press accounts as well as the blog entries and articles about this resolution and the vote that passed it are legion. This Google search will get you started.
3An on-line petition was signed by somewhere around 300 people, mostly astronomers affiliated with U.S. institutions. You can see the petition here.
4In 1956 the astronomer G. P. Kuiper revived an earlier theory that Pluto had been one of Neptune’s moons. This theory had originally been suggested by R. A. Lyttleton in 1936. See, R. A. Lyttleton, “On the possible results of an encounter of Pluto with the Neptunian system,” Monthly Notices of the Royal Astronomical Society, 97(1936), p.108; Willem J. Luyten
Science, NS Vol. 123, No. 3203 (May 18, 1956), pp. 896-897; Gerard P. Kuiper, “The Planet Pluto,” Science NS Vol. 124, No. 3216 (Aug. 17, 1956), p. 322; “Downgrading of Pluto,” The Science News-Letter Vol. 70, No. 10 (Sep. 8, 1956), p. 150..
5See Ann Ewing, “Pluto Theories Crumble,” The Science News-Letter Vol. 86, No. 14 (Oct. 3, 1964), p. 213.

Tags: astronomy, historiography, planets, pluto


Comment posted by laurele on 01/04 at 01:42 PM

Since you are reviewing the literature on Pluto, please visit my Pluto Blog at . I am a writer, amateur astronomer and astronomy graduate student who has actively advocated Pluto’s reinstatement for the last three years and did a presentation at the Great Planet Debate, held in August 2008 at the Johns Hopkins University Applied Physics Lab. I am in the process of writing a book about Pluto. In the meantime, I urge you to check out Alan Boyle’s book “The Case for Pluto.” Feel free to contact me at

Comment posted by laurele on 01/04 at 01:42 PM

There is no reason that Pluto, Haumea, Makemake, and Eris cannot be dually classified as both planets and Kuiper Belt Objects.

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