Mapping the Milky Way

A Radio Astronomy-Directed Investigation for Lecture-Based Astro 101 Courses

  • Kathryn Williamson West Virginia University
  • Dan Reichart University of North Carolina, Chapel Hill
  • Colin Wallace University of North Carolina, Chapel Hill
  • Edward Prather University of Arizona, Center for Astronomy Education
  • Seth Hornstein University of Colorado, Boulder
Keywords: radio astronomy, Skynet, Astro 101, Milky Way


The Green Bank 20-meter radio telescope integrated into the Skynet Robotic Telescope Network offers a unique opportunity to engage learners in investigations that are not possible with optical telescopes.  Radio investigation of the Milky Way using the neutral hydrogen (HI) 1420.41 MHz emission line have a long history with the educators at Green Bank Observatory and through the Skynet team.   The project discussed considers how best to adapt these investigations into a large-enrollment, general education, introductory college astronomy course (“Astro 101”). Astro 101 courses serve over 250,000 students nationwide each year. To conduct a class-wide investigation of the Milky Way, we first have each student collect a 60-second radio spectral scan of the HI emission line for a single portion of the galactic disk.  Once this class data over a wide range of galactic longitudes is combined, the students can use simple geometry and Doppler information to determine that we live in a spiral galaxy and that we orbit the galactic center clockwise (if looking down on the Galactic North Pole). Together with archived data of the Large and Small Magellanic Clouds, a galactic rotation curve and an enclosed mass curve can be created to illustrate the “missing mass” problem as evidence for existence of dark matter. Results from a formative assessment illustrate that this project helps students connect concepts learned in class and gain confidence in their abilities to do scientific research. Activity lecture slides and data spreadsheets are freely available.