Use Astronomy to Teach Physics
Modern astronomy and space science have brought us remarkable technologies and astonishing discoveries that excite and engage us all—teachers, students, and the general public. But it is physics that lets us explore and comprehend the cosmos and its unusual objects, and we need to help our students understand this physics. This theme issue shows how we might improve this process by using astronomy’s discoveries and technologies as contexts for teaching physics.
How can we use astronomy to teach physics? The articles in this issue suggest answers that are varied and interesting. Implicitly, they also raise some important questions. For one thing, how do you find a focus when there is such a dazzling wealth of material and such a vast range of possibilities? How do you bring your attention to bear on the underlying physics without being swept away by powerful images and narratives? For another thing, physicists need to know astronomy if they are going to use it to teach physics; for many of us this means learning new ideas, new vocabulary, and new ways to look at the Universe and its parts. It may also mean learning some new physics.
How can we learn what we need to know? Tutorials are one way to learn. An example in this issue is the account of distances and times in observational cosmology and the useful synopsis of the theory that underlies these concepts. You’ll also find in this issue a research-based analysis of how to help students understand expanding space-time. Additionally, this issue has some articles focused on particular questions. These questions can be valuable adjuncts to a tutorial. Students may ask, “Why don’t stars or galaxies expand as the Universe expands?” or “How did the Big Bang get started?” You’ll want to think about such questions before you start teaching the subject. Together, these articles point the way to making an effective introduction to some exciting physics.
And, of course, we continue to use old astronomy and old physics. Seventeenth century astronomy helped Galileo, Kepler, and Newton invent physics that is still important. You need it to send missions into space; you need it to find exoplanets. It also enables you to have some fun by analyzing pictures of dust kicked up by the Lunar Rover to find the acceleration of gravity on the surface of the Moon. One of Galileo’s great ideas, we are reminded, is that physics works everywhere, not just on Earth.
Astronomers, astrophysicists, and space scientists work hard at outreach. Their efforts have created a large body of web-based materials that explain astronomy’s basic concepts and offer technical details about major instruments and space missions. Physicists can adapt these materials for physics instruction. Online archives of astronomical data are another resource for physics courses. But we need to know more about what materials are available, and we need to imagine creative ways to use them. Moreover—and this is quite exciting—you can now acquire your own data using remotely operated telescopes. Two articles in this issue focus on these topics. Who knows, you might even discover your own exoplanet or asteroid!
Or you can gather your own data by going outside and looking up. Read here how, with modern conveniences, students use the astronomy of thousands of years ago to size the Earth, find the scale of the Solar System, and determine distances to nearby stars.
The power of astronomy to motivate interesting physics may be especially useful in higher-level physics courses. After all, the possibilities are many and alluring. There is a bestiary of fascinating objects: pulsars, black holes, magnetars, neutron stars, quasars, red giants, brown dwarfs, and a roster of phenomena: novae, supernovae, stellar evolution, nucleosynthesis, jets, and gamma-ray bursts, any of which can provide a framework for teaching interesting physics. It was astronomy that focused one author’s attention on the physics of the negative hydrogen atom and the behavior of atoms in a strong magnetic field.
The technologies of astronomy are also a rich source of topics. Charge-coupled devices, bolometers, millimeter radiation sensors, x-ray and gamma ray detectors, radio telescopes and radio interferometers, multi-mirror telescopes, gravity wave detectors, neutrino observatories, adaptive optics, space observatories, and computation and data handling—all offer frameworks for teaching good physics.
To gather this harvest you need a taste for adventure. You need to be willing to try something new. But be warned that it will not be easy. When you read the article analyzing the behavior of electrons in Earth’s magnetic field, realize that its author is refuting the physicist who, when asked how to get more plasma physics into the undergraduate curriculum, replied: “Don’t bother. It’s just too hard.”
“Too hard to teach” is an in-your-face challenge. Let’s take it on, whether it’s plasma physics or cosmology or general relativity or any other topic. Be inspired by the articles in this issue, and then come to the Gordon Research Conference on “Astronomy’s Discoveries and Physics Education” and help meet the challenge.1
Charles H. Holbrow, Colgate University and MIT
Peter Shaffer, University of Washington
Theme Issue Editors
1 The 2012 Gordon Research Conference on Physics Research and Education will be held June 17-22, 2012 at Colby College, Waterville, ME. More information and application information is available at <http://www.grc.org/programs.aspx?year=2012&program=physres>.