effect came from studies of Venus, whose surface temperature exceeds 800 degrees Fahrenheit because of a thick atmosphere of carbon dioxide. The first understanding of rapid global climate change came from computer models of the effects of nuclear war, and of catastrophic asteroid impacts that led to a mass extinction 60 million years ago. One of the best ways to investigate the complex problem of how Earth’s climate responds to stress is to study the geological record of changes induced by periodic changes in Earth’s orbit over the past few million years. A better understanding of the Sun is also critical to modeling and understanding climate change. Over the past few decades, as computational power has increased, our fundamental understanding of how the Sun works has been improving dramatically.

One of the most ambitious efforts to solve the nation’s energy problems involves the development of controlled nuclear fusion. Nuclear fusion was first understood early in the last century by astronomers seeking the energy source of the stars, and since then there has been a close and fertile collaboration between astrophysicists trying to understand the behavior of plasmas in astrophysical systems and fusion researchers working to control plasmas in the laboratory; indeed, the U.S. fusion program was started by the same astronomer, Lyman Spitzer, Jr., who first proposed the concept of a space telescope.

Astronomers can bring to these initiatives their relevant experience, capabilities, and expertise in the atmospheres of planets and stars, radiative transfer, fluid dynamics, nuclear physics, plasma physics, electronics, detectors, remote sensing, numerical simulation of complex systems, and data handling, as well as one of their most important skills—the ability to draw reliable inferences from incomplete observations as opposed to controlled experiments.

One of the more important communication challenges for science as a whole and astronomy in particular is in the area of public policy. Given that the practical outcomes of scientific investigations often play a key role in our economic prosperity and quality of life, and as scientific projects grow in size and complexity, it is important and useful for scientists and people with technical backgrounds to be engaged in the public policy process and to understand constraints in the funding of research.