INSTRUCTOR’S NOTES Chapter 1 is an introduction to the measures and methods of astronomy. Major topics include ▶ our cosmic address; that is, the hierarchy of structures from solar systems to superclusters ▶ an intuitive scale of the universe ▶ relevant and relative distance scales, including the lightyear and light-travel time ▶ the scientific method and relevant vocabulary; that is, distinguishing theory from idea ▶ reading graphs and using trends or patterns to understand data Greetings, fellow professors! Whether you are using this textbook to teach a one semester or a yearlong astronomy course, to teach nonscience majors for general education credit, or to teach prospective physics and astronomy majors, you have an auspicious and audacious task ahead of you: to teach the whole universe, from the unimaginably small to the incomprehensibly large. As Dr. Mike Seeds of Franklin & Marshall College explains, “The Universe is very big, but it is described by a small set of rules and . . .we have found a way to figure out the rules—a method called science.” It is my hope that I can share in these “Instructor’s Notes” some successes and failures, tips and traps, in teaching this material to a diverse audience. At the beginning of every course, I provide to students an anonymous survey in which I ask them to rate their comfort and previous experiences with math and science, and a majority usually report that they consider themselves to be bad at math and afraid of science. Over nearly two decades of interacting with introductory astronomy students, I have found that they report a few common themes. First, they think that physics and astronomy are only about doing math problems, and second, much of their discomfort comes from previous experiences in which they were assumed already to be well versed in the vocabulary of science. Much as I do in my first lessons, this chapter aims to ease students into the astronomy curriculum by addressing both of those issues. Astronomy deals with numbers that span the gamut from the subatomic to the whole universe. I may be quite comfortable discussing wavelengths in nanometers, particle densities in atoms per cubic centimeters, masses in 1030 kilograms, and distances in gigaparsecs, but I find it useful to conduct exercises with Figures 1.1 and 1.3 or show a version of the “Powers of Ten” montages to provide students with some visual context for the ranges of size, mass, speed, and time that are discussed in this course. Much of the quantitative problem solving in this course can be achieved through proportional reasoning (that is, how does brightness change if distance triples?), so in addition to asking questions about scientific notation and unit conversion, I introduce some basic ideas of how area or volume changes with size. For many of my students, this is the last formal science course they will ever take, so one of my learning outcomes is that they learn the process of science, gain scientific literacy, and understand the difference between science and pseudoscience. The seeds of these outcomes are sown in this first chapter through discussion of the scientific method and of the various logical fallacies presented in the Exploration section. Although science is ideally independent of culture or creed, it has often collided with religious or other strongly held beliefs. Therefore, because science is a human activity carried out by individuals who may hold nonscientific beliefs, I emphasize that we must construct safeguards within our work to counteract any personal bias that might taint their results. Thus, science is all about searching for objective truths that lead to conclusions that are repeatedly found to be unfalsifiable. DISCUSSION POINTS ▶ Have students look at the sketches shown in Figures 1.1 and 1.3. Ask them if they are familiar with any of the shapes and structures shown. Where have they encountered them before? ▶ Have students think about the times given in Figure 1.3. Discuss the distances and times between our planet and nearby stars, and relate that to the likelihood that we will communicate with extraterrestrials in our lifetime