Learning by the Sun: Observing Seasonal Declination with a Vertical Sundial

We designed and constructed a sundial for the purpose of observing the declination of the sun and thus marking solar seasonal variation. The 122 × 122 cm vertical sundial on the south-facing wall of our library has two unusual features: a nodus on the gnomon that casts a shadow of a point for markin...

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Bibliographic Details
Published in:Journal of science education and technology 2003-03, Vol.12 (1), p.81-88
Main Authors: Klein, Judy L., Riskin, Adrian
Format: Article
Language:English
Subjects:
Altitude
Azimuth
Declination
Design
Earth Science
Equinoxes
Fall lines
Geometric Concepts
Geometric lines
Marking
Mathematics Education
Observational learning
Physical Sciences
Science Activities
Science Instruction
Seasonal variations
Secondary Education
Shadows
Solar observatories
Solstice
Students
Sun
Sundials
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Summary:We designed and constructed a sundial for the purpose of observing the declination of the sun and thus marking solar seasonal variation. The 122 × 122 cm vertical sundial on the south-facing wall of our library has two unusual features: a nodus on the gnomon that casts a shadow of a point for marking the height of the sun and a large blank working space for students to mark the shadow of the nodus at different hours of the day and to connect the marks of 1 day in a line of declination. We discuss the design of a dial that emphasizes a working space for observations on solar declination, methods for determining the position of the nodus such that lines of declination can be observed every day of the year, mathematical procedures that minimize error in laying out the hour lines for this unusual design, the type of materials that are best suited for this design, and how students in an interdisciplinary honors colloquium on seasonal rhythms used the sundial. We also include two appendices on general sundial construction that indicates the information designers need to construct their own sundials.
ISSN:1059-0145
1573-1839
DOI:10.1023/A:1022115829592