AstroMedia: The Solar Compass

AstroMedia: The Solar Compass

With the help of this simple device, the cardinal directions can be determined accurately even without a compass. For this purpose, the movement of the sun´s shadow must be observed and marked for one day.

How to do it}]
Align the solar compass on a well-sunned, horizontal surface to the point where the sun is at noon. Then for one day, at least before 11 a.m. until after 2 p.m., follow the movement of the shadow and mark the points exactly where the tip of the shadow touches one of the circular lines. In the evening, the two points of contact that lie on the same circle are connected with a line. These lines lie exactly in the east-west direction. If you halve these lines and connect the halving points with the center of the circles, you get a line running exactly north-south.

[*The Indian Circle
This method is called the "Indian Circle". It was already known in ancient times and is also perfectly suitable to be transferred to the scale of a large area, e.g. a schoolyard. All you need is a string compass and a long wooden stick.

For teachers and students
The solar compass is easy to build and is an excellent teaching aid for secondary schools. It can be used, just like all other astro materials, of course also in other group and project work on the subject of astronomy and physics.

This is what you still need for the assembly

a firm, even work surface

a sharp cutter knife

a good all-purpose glue

some fine sandpaper

a sharp pair of scissors