Maya Falck, Scott Godsen, and Rebeca Waysek, teachers at The Spence School in New York City, New York, were inspired by an activity developed through NASA’s Kepler Space Telescope site that demonstrates the technique of using planetary transits to identify new exoplanets. The teachers adapted the concept by creating an experiment using a Vernier Light Sensor in order to conclude what patterns scientists should look for in determining the size and orbital speed of an exoplanet orbiting distant stars.
For the experiment, a Light Sensor, which represents the Kepler spacecraft, is positioned facing a light source, which represents a star. Relative variations in light intensity and duration are measured as students move various-sized foam balls between the Light Sensor and the light source. Students helped to design the procedure, and the experiment calls for students to roll the balls along a plastic race track, releasing them at various heights to control the speed. There are physical limitations to modeling transits in this way, specifically the relative distance between the light source, the exoplanet, and the sensor; however, students explore these limitations as part of recording and evaluating their results.
Notes for using this experiment in your classroom: As part of reviewing the setup with students, be mindful of the relative separation between the light source (flashlight), the Light Sensor, and the track. The students should identify this as something to be held constant for the experiment, but they won’t likely be aware of the impact of having the sensor too close to the track or the light source. If the track is too close to either the light source or the sensor, the differences in intensity changes between different sized spheres will not be as dramatic. If space permits, arrange for at least 50 cm between the track and both the sensor and the light source.