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Paper Plate Education
"Serving the Universe on a Paper Plate"

Activity: Altitude Co-Altitude

C-Nav_Altitude_done.jpg (43397 bytes)

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.   

C-Nav_Altitude_horizon.jpg (11268 bytes) C-Nav_Altitude_horizon_zoom.jpg (42302 bytes) Make a horizon plate with window cut out as shown.  The sailboat's mast points to the zenith.  The waterline defines the horizon.

C-Nav_Altitude_pointer.jpg (12543 bytes) C-Nav_Altitude_pointer_zoom.jpg (12377 bytes) 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.

C-Nav_Altitude_done.jpg (43397 bytes) C-Nav_Altitude_done_zoom.jpg (14672 bytes) 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.

 

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