Queen Anne’s County middle school students explore polarized light at UMBC’s ESI

Mon, 21 Apr 2025 15:44:07 -0400
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On April 4, 2025, 8th grade students from Queen Anne’s County visited UMBC's campus as part of a broader campus tour. The youth visit was led by Dr. Sarah Gardenghi, Assistant Vice Provost of Educational Pathways and Partnerships at UMBC. The students met with current undergraduate students to hear their perspective on college and participated in an activity related to research going on at UMBC. For the activity, the students visited the Earth and Space Institute, where ESI scientist Dr. Brent McBride demonstrated how climate scientists use light to learn more about Earth’s climate (see photo).

Photo: Dr. Brent McBride chats with several students about the difference between corn syrup and vegetable oil under polarized light. Photo Credit: Sarah Gardenghi/DPS.

The students used linear polarizer sheets to change the light passing through common household objects, such as transparent cutlery, corn syrup, and vegetable oil. Depending on the material, the color of these objects changed dramatically or had no effect at all when a polarizer was rotated in front of it. For example, rotating a polarizer in front of the cutlery produced beautiful rainbow-like stress patterns. Dr. McBride put transparent packing tape in various directions over a glass plate, as well. When observed through a polarizer, a mosaic of rainbow shapes and polygons appeared. These colors changed from teal to purple and orange as the observing polarizer was rotated (see photo).

Photo: The spoon observed in visible (top left) and between polarizing filters (top right), and the tape mosaic observed in visible (bottom left) and polarized light (bottom center/right). Rotating the observing polarizer (in front of the camera) to different angles creates a different color pattern. Photo Credit: Brent McBride/ESI.

The tape, transparent plastic, and corn syrup can act as wave plates. These filters alter how much and the content of the light that passes through based on the wavelength of the light. The differing index of refraction between the objects and the air, as well as their molecular composition and surface shape, can also impact how much color or brightness is observed.

Polarization imaging technology is currently used by ESI’s HARP2 instrument on NASA’s Plankton Aerosol Cloud ocean Ecosystem (PACE) mission. Climate scientists can use HARP2 polarized imagery to distinguish dust vs. smoke, liquid water droplets vs. ice crystals, and surface or ocean signals from the atmosphere in both familiar and new ways.