Robert Rosner is currently the William E. Wrather Distinguished Service Professor in the astronomy/astrophysics and physics departments of the University of Chicago and its Enrico Fermi Institute. His research has involved analysis and modeling of solar and stellar observations and the study of fluid behavior in the laboratory and in space, especially in the context of stellar convection and stellar magnetic field generation.<p> Anyone visiting the High Altitude Observatory will immediately sense that HAO is different: It is much more akin to a university academic department than one would ordinarily expect of a research division at a national laboratory. I would like to discuss the origins of this difference and to comment on the justifications for maintaining itindeed, for celebrating it.
Astrophysics as a discipline separate from astronomy had its origins in the elucidation of visible light spectra from the Sun and stars. A number of the giants of 19th-century U.S. physics understood the tremendous potential importance of spectroscopy in revealing the fundamental nature of matter. These early studies largely regarded the Sun as a representative astronomical object. Relatively few scientists paid attention to the Sun in itself or as the driver of activity within the solar system. Charles Abbott's work on the terrestrial impacts of the Sun, for example, was isolated from the mainstream of astrophysicalor even solarresearch.
With the advent of quantum mechanics in the 1920s, it became possible to establish quantitative connections between observations of solar spectra and physics questions such as the elemental composition of the solar surface. Observations of the Sun, especially of the solar corona, played an important role in the development of atomic physics. Two scientists centrally involved in the founding of HAO were in the thick of this kind of research in the late 1930s: Donald Menzel, a professor of astronomy at Harvard and the director of the Harvard College Observatory, and his student Walter Orr Roberts. Harvard established HAO in Climax, Colorado, to improve observations in this field. The coronal observations carried out at Climax set the theme for much of the science carried out by HAO to this day; the observatory's coronal section is the standard bearer of this branch of solar research.
Thus, originally, HAO was a remote station for a quintessentially academic research program. Its sole reason for existence was its contributions to the furtherance of basic science objectives. HAO's science program was entirely developed internally, with no need to justify itself to any external agents, and the quality of the science was the sole benchmark by which the observatory was judged. Over the 60 years of HAO's existence, this academic model has continued to influence the way science is carried out there.
The view that the Sun is interesting in its own right, without additional justification, motivated most of the expansion of HAO's research areas since its inclusion in NCAR: the fundamental work on radiative hydrodynamics, the solar wind, the solar dynamo, helioseismology, and (most recently) stellar activity. With this perspective on solar physics, it is not surprising that HAO has historically played an important rolein some areas at some times, the dominant rolein the field on the international level. In certain important subfields of astrophysics, such as theoretical and observational radiation hydrodynamics, it is today the primary institution in the United States.
Walt Roberts was motivated to join HAO with NCAR, however, for a different kind of research: to investigate the terrestrial impacts of the Sun. In this area, I contend that Roberts was extremely insightful but demonstrably scientifically premature. Connections between solar activity and terrestrial phenomena of climatological or meteorological significance have proved to be extremely subtle and difficult to establish. Nevertheless, with modern observational tools and analysis methods, such connections are now being established. With these successes, I predict that solar physics within HAO will experience to a much greater degree than heretofore the (hopefully creative) tension that seems to naturally arise between the basic and more applied sciences. The challenge for HAO will be to balance the historical pressure for excellence in basic solar science with the increasing pressures for practical relevance.
The tension between basic, unfettered research and applications- driven research has existed to some extent since HAO joined NCAR, and, of course, it pervades much of what NCAR is about as well. From its inception, however, NCAR has strongly connected with the larger atmospheric sciences community on a wide variety of fronts, including the definition of its science programs. To the extent that HAO succeeds in Walt Roberts' scientific ambitions, it will feel increasing pressure to expand its community-based outlook.
It is my view that applications-oriented science best maintains rigor and discipline when it is closely coupled to a basic science component. But it is also my view that the basic sciences strongly benefit from this kind of coupling as well: The applications provide motivations and directions which the basic sciences at times cannot provide internally. For these reasons, as the connections between solar physics and the atmospheric sciences grow stronger and are placed on increasingly firmer quantitative grounds, I see HAO in a unique position to benefit both itself and the larger scientific community. I therefore salute HAO and its scientists for what they've wrought; and I am excited about their future.