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(System requirements: DOS 3.0 or higher. Printouts require an HP Laserjet printer.)
Planet Tracker is available for download under the name PLTVER42.ZIP from the astronomy software archive at SEDS (in their solar system subdirectory). It is shareware, but we ask that you register if you make regular use of this program.
Planet Tracker (for MS DOS computers) is an innovative presentation of planetary motion. The software design is by David Chandler and the accompanying text materials are by David Chandler and astronomy textbook author Michael Zeilik, both active astronomy teachers. Planet Tracker differs from general purpose planetarium software in its ease of use by students and its specific conceptual focus.
Planet Tracker is built in three modules:
Motion Along the Ecliptic displays the motions of the sun and any or all of the naked-eye planets against the background of the Zodiac stars. Running counters display the date and Julian Day, allowing quantitative questions to be explored. The animation can be single stepped or run in continuous mode, optional trails can be drawn, and vertical exaggeration can be introduced to display the retrograde loops in more detail. At any time the animation can be frozen and the planets can be identified by name.
Split Screen Animation displays planetary motion from five different points of view, allowing any two to be compared side-by-side. The five viewpoints are: the apparent dome of the sky for a fixed time of day, the zodiac as seen from the Earth, heliocentric solar system, geocentric solar system, and a special rotating frame of reference holding both the earth and sun stationary. At any time during the animations, rays can be drawn from the earth to each planet, showing that the essential geometry is preserved despite the apparent differences in the viewpoints.
Basic Worksheets produces heliocentric and geocentric orbit diagrams and time lines for any given starting date. In situations where computers are not available for direct access by students the worksheets provide a solid core of material for in-class activities that teach planetary motion concepts. The worksheets are the basis of many of the lab activities in the on-disk lab manual. They are also useful for making overhead transparency masters and observing aids to be taken outside at night. (A standard dot matrix or HP Laserjet printer is required. Unlike Deep Space, Planet Tracker has not been converted to Postscript.)
An extensive content-oriented help file and on-disk lab manual (ASCII files) will help you understand the capabilities of the program and its immediate usefulness for your introductory astronomy classes.