slightly behind the fraction for physical sciences overall. Although many foreign astronomers are expected to repatriate, the globalization of research, discussed above, ensures that many are likely to continue to contribute to the U.S. astronomical enterprise.
About 70 percent of the astronomy Ph.D. holders who remain in the United States after obtaining their degrees hold fixed-term postdoctoral positions before gaining long-term employment (Figure 4.12). Some postdoctoral positions are prize fellowships supported either by agencies (e.g., NASA’s Einstein, Hubble, and Sagan fellows; NSF’s Jansky fellows through NRAO and astronomy and astrophysics postdoctoral fellows) or by private donations to individual universities. These highly competitive fellowships allow independent research programs in a large range of subfields. Other postdoctoral positions are tied to a specific sponsored research grant or project. It is quite common for astronomers to hold two or three successive postdoctoral positions of 2 to 3 years each, so that many astronomers are in their mid- to late-30s before finding long-term employment. One consequence of this delay is the added difficulties for family life, which can also compound the problem of attracting women to the field.
Data from the AAS Job Register indicate that the number of postdoctoral positions advertised every year has doubled over the last decade, whereas the number of advertised tenure-track positions and long-term research or support positions15 has decreased slightly. Some of these positions are taken by foreign applicants, and some U.S. postdoctoral scholars take up employment elsewhere. Overall, the production rate of astronomy Ph.D.s exceeds the current rate of long-term astronomy faculty opportunities by a factor of at least three, which is a point of great concern to young astronomers (Figure 4.13). Recently this problem has become much more acute because of a decrease in the number of faculty openings due to hiring freezes and postponements of retirement for economic reasons. However, from the data shown in Table 4.1 plus an understanding of the diverse set of job functions held by those at research universities, it can be inferred that traditional teaching faculty positions are less than half of the permanent positions held by AAS members.
Astronomy is an incredibly exciting field that is attracting some of the best and brightest technically able young people. They are a precious resource for the nation, and it is important to optimize and broaden the benefits to the nation that their talents bring. Young people trained in astronomical research have a high degree of competence in disciplines with applicability beyond just astronomy and astrophysics. As a group, they are also energetic, hard-working, and highly motivated, and the fraction of their time that can be devoted to research is higher than at earlier and later career stages.