Paper Plate Education
Activity: Altitude Co-Altitude
Demonstrate how altitude (Ho) is the observed height of a star or sun and how co-altitude (90°-Ho) is the complement of the measured altitude. Also known as the zenith distance, co-altitude equals ninety degrees minus the observed height of the sighted star or the sun.
Make a pointer plate as shown. Cut out the line of sight to the star partway, from the edge of the plate to the colored arcs. Altitude (Ho), the measured angle from the horizon up to the sighted object, is depicted with the orange arc. Co-altitude (90°-Ho), the measured angle from the zenith down to the sighted object, is depicted with the yellow arc.
Combine the two plates as shown. The orange arc shows the altitude; the yellow arc shows the co-altitude. To quantify with numbers what this plate conveys visually, calibrate the edge of the plate from horizon to zenith
Contributed by Chuck Bueter.
Copyright ©2012 Chuck Bueter. All rights reserved.