Statistics and Classification of the Names

This dictionary contains information on all 10038 planets which had been named at the end of 2002. The object (1) Ceres was discovered on January 1, 1801 and is thus the 'eldest' numbered and named planet; (50000) Quaoar was discovered only on June 4, 2002 and represents the latest named planet. Overall 52224 planets were numbered up to the end of 2002. The distribution of the discoveries during the more than two centuries can be taken from the cumulative diagram Fig. 1. The immense increase of the rate of discovery during the last years is obvious. One century after Piazzi, less than 1% of the planets that are now numbered had been discovered. The number 1000 was surpassed in

1921; the number 2000, shortly after World War II. The progress of the numbering process during the last few years has been extremely rapid. It is therefore appropriate to measure the evolution in terms of consecutive ten thousand newly numbered objects - minor planets (10000) - (50000) were numbered in March 2000, June and October 2001, and in May and November 2002!

Brian Marsden (1979), Director of the Minor Planet Center and a leading expert in this field, enormously underrated this evolution when he said: "At the present and anticipated future rate of growth, it is not unreasonable to suppose that there will be 4000 numbered minor planets by the end of the century." He, in fact, underestimated the real evolution by a factor of five. The rate of growth becomes evident by noting that during the past 16 months (!) as many minor planets were numbered as during the span of 201 years before that. This rate of growth is all the more impressive when one notes that the standards applied to the quality of the orbital elements are now much stricter. The discovery rate of numbered planets is discussed in some detail by Bowell et al. (1989) and more recently by Marsden (1996). However, both papers gave results which are completely untenable today. Actually we are faced with the fantastic doubling rate of minor planet num-berings of approximately 4 years - the first 4096 = 212 objects were numbered by 1989 and this number grows to 32768 = 215 at the end of 2001. Nowadays we must predict that there will be 216 numbered planets during 2004. Presumably this tendency will be flattened out in forthcoming years because of saturation effects in the observing as well as data handling capacities. One has to bear in mind that at peak times observational data are reported to the Minor Planet Center with a frequency nearing 1 Hz!

The data base also reveals the discovery frequency according to seasons in the year (see Fig. 2). Because of the weather conditions, there are discovery maxima in spring and in autumn. The differing heights of the

100 80 60 40 20 0

1800 1850 1900 1950 2000

Fig. 1: Cumulative numbers of minor planet discoveries

9600 8000 6400 4800 3200 1600 0

JFMAMJ JASOND Fig. 2: Minor Planet discovery frequency by months maxima reflect the fact that by far most of the planets were found from the Northern Hemisphere, where relatively good conditions for observations away from the band of the Milky Way are found in autumn. The ranking list of discovery places given in Appendix 5 confirms the leading role of the Northern observatories - only two stations in the Southern Hemisphere rank among the first ten places. Due to the establishment of special minor planet survey telescopes this situation will significantly evolve towards an even larger asymmetry in the near future. The errection of a powerful southern station is strongly recommended.

As of January 2003, out of a total of 52224 planets which have been given numbers, only 10038 or 19.2% have been named. In general, the earlier a planet was discovered, the sooner it was named. For example, each of the first 3300 planets were assigned a name. Unfortunately, the naming ratio seriously dropped off during the last few years. While this ratio was nearly constant with 75 - 80% at the first half of the last decade, it decreased to approximately 60% at the end of the millenium. Reasons for the delay in the naming process which unfortunately reduces the security of redundancy are the lack of staff at the CSBN and the MPC. Occasionally, a limitation (e.g., by the magnitudes) or even a general stop of the naming was considered. Figure 3 demonstrates that the completeness of names declines considerably with higher numbers.

There has always been a preference for names consisting of a single word. This rule could not be maintained, however, since the names of some of the people to be honored consist of two or even three words. Thus 178 out of 10038 names combined of more than one word had to be tolerated. A total of 82 designations contain a hyphen, and 46 an apostrophe. For some time a diacritical mark, such as an umlaut could not be adequately represented by data processing machines. The use of diacritical marks causes no such problem with machine-readable data now, and consequently such marks are found in 529 names. The length of a chosen name is also interesting. Names

100 1111

0 10000 20000 30000 40000

Fig. 3: Fraction of named minor planets

0 10000 20000 30000 40000

Fig. 3: Fraction of named minor planets consisting of a single character have never been accepted. For reasons of data processing, however, a maximum length of 16 characters was adopted. Unfortunately, this rule was violated in the special case of (4015) Wilson-Harrington. The following table shows the present distribution of the length of names:

Number of characters

Minor Planet names

Number of characters

Minor Planet names

2

7

10

830

3

101

11

611

4

514

12

375

5

1129

13

192

6

1664

14

110

7

1692

15

61

8

1556

16

32

9

1162

17

1

not classified by countries. Nevertheless, as can be seen in Appendix 7, the statistics on some 7650 classifications is quite informative. There is a clear predominance of the 'great powers' in the field of minor planets: names that can be definitely assigned to a country come mainly from the USA or the former USSR, followed by Japan, Germany, France, Italy and the Czech and Slovak Republics. The USA and especially Japan became outstanding only during the last decades. The USSR and Germany owe their ranking mainly to the observatories at Simeis/CrAO, Heidelberg, and Tautenburg, respectively. The preponderance of countries from the Northern Hemisphere is striking.

After the publication of the first edition of this "Dictionary" some very useful papers dealing with name classifications have been appeared. Combes (1993) published a very interesting list with free classification criteria. Schmadel (1992) compiled a special catalogue of astronomers belonging to the European Southern Observatory (ESO). Special investigations concerning names with close relations to certain countries have been undertaken by Meeus (1988), Denoyelle (1995/96) and by Schnell and Haupt (1996).

Classification according to other criteria is not so straightforward. After several attempts we found 19 rough categories which came up rather automatically. In this way more than 95% of all names could be classified, compared to only 76% according to a classification based on country. A first analysis shows that the names of minor planets do not reflect an 'astronomers' cemetery,' a 'female sky,' or even an 'Iliad sphere,' as has often been suggested. There are, however, periods during which the naming could be so described.

About one half of the names consist of six to eight characters. There is a certain overabundance of names consisting of four characters. This is due to an old rule to assign planets a four-letter name if their orbital elements have exceptional characteristics. This rule is now rarely applied. With an increasing number of names difficulties arise when names are too similar. We therefore observe a slight trend towards longer names. This will in part be compensated by the proposal to limit concatenated or contrived names of people to 12 characters.

The names may be classified, of course, according to many different criteria. We decided to arrange groups of countries and groups of free classification. Names dedicated to countries, cities, rivers, buildings, etc., can be classified very easily. There may be difficulties, for example, in assigning names of astronomers, artists, or other people to only one country if they happen to have worked in several different ones. Names from mythology cannot be assigned to a particular country. Names given in honor of a discoverer's relatives were, as a rule,

Mythological names predominated only in the first three quarters of the 19th century. Later, classical names were almost exclusively invoked for the Trojans. These are divided (with some unfortunate mistakes) into groups of Greek besiegers and their Trojan opponents. The Trojan planets are distinguished by their 1:1 resonance with Jupiter. They were given male names in contrast to the normal, 'female' planets. This anti-feminine character shows as well in the clear preponderance of male names to female names, in the ratio of 4 to 1: as far as naming minor planets is concerned, emancipation has not yet been very successful.

The suspicion that a cemetery for astronomers has been founded cannot be substantiated either, since only a bare quarter of all names refers to this profession. Appendix 6 shows that many other scientists have been honored, and the list of amateur astronomers is also remarkable. The list of names referring to relatives of the discoverer have decreased considerably in comparison to the figures from earlier editions. As an analogy to characters from classical mythology, genealogical tables can be reproduced. An example with the names of relatives suggested by the discoverer couple Carolyn and Eugene Shoemaker is given in Fig. 4.

Without going into details we see that spouses of the patrons prevail over their children as well as over their parents. It is much easier for a grandchild to become astronomically immortal than it is for a grandparent. And the uncles and aunts of the discoverers are much less represented than their friends.

A quickly increasing group is given by the amateur astronomers as well as famous scientists outside of the field of astronomy. Distinguished musicians, painters, and writers constitute a substantial group of names. Dramatists and novelists are still prevailing in the group of intellectuals, but musicians and composers are coming up rapidly. One can also try to find out if a particular discoverer tends towards names in particular categories. One can see personal preferences very clearly, but trends common to many discoverers only rarely. Today, plants and animals are seldomly chosen, whereas acronyms and abbreviations are in fashion. Somewhat to our regret, there are not many entries in the category of curiosities. This is a wide field for imaginative discoverers.

Planets named in honor of famous contemporaries can be further analyzed and arranged into subcategories. This is shown for two groups. Appendices 8 and 9 give lists of Nobel laureates and of IAU officers who gave reason for being honored with a planet's name. Remarkably, not only physics prize-holders were honored. Considering the great number of all Nobel laureates, this list is rather short. This is very different from the list of astronomers who were once officers in the IAU, the discoverers' professional representation. Here we find nearly no gaps and one can assume that remaining ones will soon be filled.

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