Astronomy's Stars

Sky surveys sometimes reveal unexpected gems, such as unknown planets or variations in the cosmic microwave background. But the latest astronomical survey--from the folks who track scientific citations--would seem to confirm a no-brainer: The most influential institutions are those with the most scientists. The survey did, however, spot some smaller stars in the astronomy firmament whose contributions have a disproportionately large impact. The rankings appear in the November/December issue of ScienceWatch, published by the Philadelphia-based Institute for Scientific Information (ISI).

ISI ranked institutions according to the number of times a paper was cited by other papers. The tabulators looked at papers in space-science journals and pertinent papers in Science and Nature published between 1993 and 1995. Rankings were limited to institutions that produced at least 30 ``high-impact'' papers--papers cited more than 10 times.

NASA weighed in as the heaviest of heavy hitters. NASA-Goddard Space Flight Center and the NASA-sponsored Space Telescope Science Institute are first and third in total number of citations. That's no surprise, says NASA-Goddard astronomer Steve Maran. ``There you have probably two of the largest concentrations of astronomers in the country'' who spend a lot of time on research, he says.

Viewed through another lens, however, the survey suggests that the real stars are smaller institutes that produced the year's hottest papers. According to a second ranking called citation impact, based on the number of citations per paper, smaller institutes tended to shine the brightest. The U.K. Royal Observatories in Cambridge and Edinburgh topped this list.

Of course, statistics don't tell the whole story. According to Virginia Trimble, an astronomer at the University of Maryland, such rankings tend to simplify complicated collaborations between institutions and fail to reflect that many astronomers gather much of their data outside their home institute. She notes that Australian institutes, which hosted many of the observations for an important catalog of distances to stars, never even cracked the top 20 on either list. Nevertheless, she says, ``the places that come out on top are places we all agree are the best.''