Most students have an intuitive understanding of how to gauge the distances to objects in their local environment. Through a combination of binocular vision and visual cues such as the perceived sizes of known objects, students can construct a three-dimensional mental model of their local surroundings, and use it to make sense of their environment.
They do not typically understand, however, that the same geometric principles behind binocular vision and depth perception are also used for quantitative distance determination by triangulation and astronomical parallax. We have built a hybrid exercise combining experiential learning with computer visualization for undergraduate students to explore distance determination in the local terrestrial and astronomical contexts in an effort to help them bridge their intuitive understanding to geometries where distance measurement is not possible visually, but is possible via more precise measurements made with instrumentation.
Students explore distance determination in an outdoor setting where the distances to objects (~50m) are too large for intuitive distance measurement, but can be determined quantitatively through a simple triangulation process. By measuring the direction to a target object from two different positions separated by a known distance, they can determine the distance to the target. This triangulation method is used by moving ships at sea, to determine the distance to, say, a visible lighthouse. It is also the method by whichastronomers measure the distance to nearby stars (In this case, the “moving ship” is the Earth in its orbitabout the Sun.).
The second component of the activity involves using the multi-perspective visualization capability of the WorldWide Telescope (WWT) virtual environment. WWT, originally developed by Microsoft Research, and now managed by the American Astronomical Society, is freely available to the world community. WWT represents real astronomical data in a three-dimensional environment that students can investigate from a variety of physical perspectives. With this software, students can compare the apparent locations of nearby stars from widely separated vantage points (much larger than the size of the Earth’s orbit),making the shifts in star positions due to the parallax effect obvious. They can see how their view of universe changes as they change their observing location, connecting their intuitive understanding of distance measurement, and their experience with terrestrial triangulation, to the astronomical realm.
Assessment data indicate that, after participating in this hybrid activity, students better connect their intuitive understanding of distance determination to the quantitative calculations required for precise measurement of distance.